Auditory training improves neural timing in the human brainstem

Neural Delays in Processing Speech in Background Noise Minimized after Short-Term Auditory Training

Background noise disrupts the neural processing of sound, resulting in delayed and diminished far-field auditory-evoked responses. In young adults, we previously provided evidence that cognitively based short-term auditory training can ameliorate the impact of background noise on the frequency-following response (FFR), leading to greater neural synchrony to the speech fundamental frequency(F0) in noisy listening conditions. In this same dataset (55 healthy young adults), we now examine whether training-related changes extend to the latency of the FFR, with the prediction of faster neural timing after training. FFRs were measured on two days separated by ~8 weeks. FFRs were elicited by the syllable "da" presented at a signal-to-noise ratio (SNR) of +10 dB SPL relative to a background of multi-talker noise. Half of the participants participated in 20 sessions of computerized training (Listening and Communication Enhancement Program, LACE) between test sessions, while the other half served as Controls. In both groups, half of the participants were non-native speakers of English. In the Control Group, response latencies were unchanged at retest, but for the training group, response latencies were earlier. Findings suggest that auditory training can improve how the adult nervous system responds in noisy listening conditions, as demonstrated by decreased response latencies.

Exposure to bilingual or monolingual maternal speech during pregnancy affects the neurophysiological encoding of speech sounds in neonates differently

Introduction

Exposure to maternal speech during the prenatal period shapes speech perception and linguistic preferences, allowing neonates to recognize stories heard frequently in utero and demonstrating an enhanced preference for their mother's voice and native language. Yet, with a high prevalence of bilingualism worldwide, it remains an open question whether monolingual or bilingual maternal speech during pregnancy influence differently the fetus' neural mechanisms underlying speech sound encoding.

Methods

In the present study, the frequency-following response (FFR), an auditory evoked potential that reflects the complex spectrotemporal dynamics of speech sounds, was recorded to a two-vowel /oa/ stimulus in a sample of 129 healthy term neonates within 1 to 3 days after birth. Newborns were divided into two groups according to maternal language usage during the last trimester of gestation (monolingual; bilingual). Spectral amplitudes and spectral signal-to-noise ratios (SNR) at the stimulus fundamental (F0) and first formant (F1) frequencies of each vowel were, respectively, taken as measures of pitch and formant structure neural encoding.

Results

Our results reveal that while spectral amplitudes at F0 did not differ between groups, neonates from bilingual mothers exhibited a lower spectral SNR. Additionally, monolingually exposed neonates exhibited a higher spectral amplitude and SNR at F1 frequencies.

Discussion

We interpret our results under the consideration that bilingual maternal speech, as compared to monolingual, is characterized by a greater complexity in the speech sound signal, rendering newborns from bilingual mothers more sensitive to a wider range of speech frequencies without generating a particularly strong response at any of them. Our results contribute to an expanding body of research indicating the influence of prenatal experiences on language acquisition and underscore the necessity of including prenatal language exposure in developmental studies on language acquisition, a variable often overlooked yet capable of influencing research outcomes.

Remediation of Perceptual Deficits in Progressive Auditory Neuropathy: A Case Study

BACKGROUND

Auditory neuropathy (AN) is a hearing disorder that affects neural activity in the VIIIth cranial nerve and central auditory pathways. Progressive forms have been reported in a number of neurodegenerative diseases and may occur as a result of both the deafferentiation and desynchronisation of neuronal processes. The purpose of this study was to describe changes in auditory function over time in a patient with axonal neuropathy and to explore the effect of auditory intervention.

METHODS

We tracked auditory function in a child with progressive AN associated with Charcot-Marie-Tooth (Type 2C) disease, evaluating hearing levels, auditory-evoked potentials, and perceptual abilities over a 3-year period. Furthermore, we explored the effect of auditory intervention on everyday listening and neuroplastic development.

RESULTS

While sound detection thresholds remained constant throughout, both electrophysiologic and behavioural evidence suggested auditory neural degeneration over the course of the study. Auditory brainstem response amplitudes were reduced, and perception of auditory timing cues worsened over time. Functional hearing ability (speech perception in noise) also deteriorated through the first 1.5 years of study until the child was fitted with a "remote-microphone" listening device, which subsequently improved binaural processing and restored speech perception ability to normal levels.

CONCLUSIONS

Despite the deterioration of auditory neural function consistent with peripheral axonopathy, sustained experience with the remote-microphone listening system appeared to produce neuroplastic changes, which improved the patient's everyday listening ability-even when not wearing the device.

Prenatal daily musical exposure is associated with enhanced neural representation of speech fundamental frequency: Evidence from neonatal frequency-following responses

Fetal hearing experiences shape the linguistic and musical preferences of neonates. From the very first moment after birth, newborns prefer their native language, recognize their mother's voice, and show a greater responsiveness to lullabies presented during pregnancy. Yet, the neural underpinnings of this experience inducing plasticity have remained elusive. Here we recorded the frequency-following response (FFR), an auditory evoked potential elicited to periodic complex sounds, to show that prenatal music exposure is associated to enhanced neural encoding of speech stimuli periodicity, which relates to the perceptual experience of pitch. FFRs were recorded in a sample of 60 healthy neonates born at term and aged 12-72 hours. The sample was divided into two groups according to their prenatal musical exposure (29 daily musically exposed; 31 not-daily musically exposed). Prenatal exposure was assessed retrospectively by a questionnaire in which mothers reported how often they sang or listened to music through loudspeakers during the last trimester of pregnancy. The FFR was recorded to either a /da/ or an /oa/ speech-syllable stimulus. Analyses were centered on stimuli sections of identical duration (113 ms) and fundamental frequency (F0  = 113 Hz). Neural encoding of stimuli periodicity was quantified as the FFR spectral amplitude at the stimulus F0 . Data revealed that newborns exposed daily to music exhibit larger spectral amplitudes at F0 as compared to not-daily musically-exposed newborns, regardless of the eliciting stimulus. Our results suggest that prenatal music exposure facilitates the tuning to human speech fundamental frequency, which may support early language processing and acquisition. RESEARCH HIGHLIGHTS: Frequency-following responses to speech were collected from a sample of neonates prenatally exposed to music daily and compared to neonates not-daily exposed to music. Neonates who experienced daily prenatal music exposure exhibit enhanced frequency-following responses to the periodicity of speech sounds. Prenatal music exposure is associated with a fine-tuned encoding of human speech fundamental frequency, which may facilitate early language processing and acquisition.

Central Auditory Processing Dysfunction in Service Members and Veterans: Treatment Considerations and Strategies

PURPOSE

Military risk factors such as blast exposure, noise exposure, head trauma, and neurotoxin exposure place Service members and Veterans at risk for deficits associated with auditory processing dysfunction. However, there is no clinical guidance specific to the treatment of auditory processing deficits in this unique population. We provide an overview of available treatments and their limited supporting evidence for use in adults, emphasizing the need for multidisciplinary case management and interdisciplinary research to support evidence-based solutions.

METHOD

We explored relevant literature to inform the treatment of auditory processing dysfunction in adults, with emphasis on findings involving active or former military personnel. We were able to identify a limited number of studies, pertaining primarily to the treatment of auditory processing deficits through the use of assistive technologies and training strategies. We assessed the current state of the science for knowledge gaps that warrant additional study.

CONCLUSIONS

Auditory processing deficits often co-occur with other military injuries and may pose significant risk in military operational and occupational settings. Research is needed to advance clinical diagnostic and rehabilitative capabilities, guide treatment planning, support effective multidisciplinary management, and inform fitness-for-duty standards. We emphasize the need for an inclusive approach to the assessment and treatment of auditory processing concerns in Service members and Veterans and for evidence-based solutions to address complex military risk factors and injuries.

The Effects of Monaural Stimulation on Frequency-Following Responses in Adults Who Can Sing in Tune and Those Who Cannot

Introduction  Musicians have an advantage over non-musicians in detecting, perceiving, and processing nonverbal (i.e., environmental sounds, tones and others) and verbal sounds (i.e., consonant, vowel, phrases and others) as well as instrumental sounds. In contrast to the high skill of musicians, there is another group of people who are tone-deaf and have difficulty in distinguishing musical sounds or singing in tune. These sounds can originate in different ways, such as a musical instrument, orchestra, or the human voice. Objective  The objective of the present work is to study frequency-following responses (FFRs) in individuals who can sing in-tune and those who sing off-tune. Methods  Electrophysiological responses were recorded in 37 individuals divided in two groups: (i) control group (CG) with professional musicians, and (ii) experimental group (EG) with non-musicians. Results  There was homogeneity between the two groups regarding age and gender. The CG had more homogeneous responses in the latency of the FFRs waves when responses between the right and left ears were compared to those of the EG. Conclusion  This study showed that monaural stimulation (right or left) in an FFR test is useful for demonstrating impairment of speech perception in individuals who sing off tune. The response of the left ear appears to present more subtlety and reliability when identifying the coding of speech sound in individuals who sing off tune.

Subcortical and Cortical Electrophysiological Measures in Children With Speech-in-Noise Deficits Associated With Auditory Processing Disorders

PURPOSE

The aim of this study was to analyze the subcortical and cortical auditory evoked potentials for speech stimuli in children with speech-in-noise (SIN) deficits associated with auditory processing disorder (APD) without any reading or language deficits.

METHOD

The study included 20 children in the age range of 9-13 years. Ten children were recruited to the APD group; they had below-normal scores on the speech-perception-in-noise test and were diagnosed as having APD. The remaining 10 were typically developing (TD) children and were recruited to the TD group. Speech-evoked subcortical (brainstem) and cortical (auditory late latency) responses were recorded and compared across both groups.

RESULTS

The results showed a statistically significant reduction in the amplitudes of the subcortical potentials (both for stimulus in quiet and in noise) and the magnitudes of the spectral components (fundamental frequency and the second formant) in children with SIN deficits in the APD group compared to the TD group. In addition, the APD group displayed enhanced amplitudes of the cortical potentials compared to the TD group.

CONCLUSION

Children with SIN deficits associated with APD exhibited impaired coding/processing of the auditory information at the level of the brainstem and the auditory cortex.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21357735.

Implementation of Machine Learning on Human Frequency-Following Responses: A Tutorial

The frequency-following response (FFR) provides enriched information on how acoustic stimuli are processed in the human brain. Based on recent studies, machine learning techniques have demonstrated great utility in modeling human FFRs. This tutorial focuses on the fundamental principles, algorithmic designs, and custom implementations of several supervised models (linear regression, logistic regression, k -nearest neighbors, support vector machines) and an unsupervised model ( k -means clustering). Other useful machine learning tools (Markov chains, dimensionality reduction, principal components analysis, nonnegative matrix factorization, and neural networks) are discussed as well. Each model's applicability and its pros and cons are explained. The choice of a suitable model is highly dependent on the research question, FFR recordings, target variables, extracted features, and their data types. To promote understanding, an example project implemented in Python is provided, which demonstrates practical usage of several of the discussed models on a sample dataset of six FFR features and a target response label.

Neonatal Frequency-Following Responses: A Methodological Framework for Clinical Applications

The frequency-following response (FFR) to periodic complex sounds is a noninvasive scalp-recorded auditory evoked potential that reflects synchronous phase-locked neural activity to the spectrotemporal components of the acoustic signal along the ascending auditory hierarchy. The FFR has gained recent interest in the fields of audiology and auditory cognitive neuroscience, as it has great potential to answer both basic and applied questions about processes involved in sound encoding, language development, and communication. Specifically, it has become a promising tool in neonates, as its study may allow both early identification of future language disorders and the opportunity to leverage brain plasticity during the first 2 years of life, as well as enable early interventions to prevent and/or ameliorate sound and language encoding disorders. Throughout the present review, we summarize the state of the art of the neonatal FFR and, based on our own extensive experience, present methodological approaches to record it in a clinical environment. Overall, the present review is the first one that comprehensively focuses on the neonatal FFRs applications, thus supporting the feasibility to record the FFR during the first days of life and the predictive potential of the neonatal FFR on detecting short- and long-term language abilities and disruptions.

The Predictive Potential of Altered Voxel-Based Morphometry in Severely Obese Patients With Meibomian Gland Dysfunction

Objective

To investigate voxel-based morphometry (VBM) by using magnetic resonance imaging (MRI) in meibomian gland dysfunction patients with severe obesity (PATs) and to explore the application of VBM in the early diagnosis, prevention of cognitive impairment and targeted treatment of this disease.

Methods

Sixteen PATs and 12 healthy controls (HCs) were enrolled and underwent MRI. Whole-head images were analyzed using VBM and data were compared between groups using an independent samples t-test. Receiver operating characteristic (ROC) curves were utilized to assess the diagnostic value of this approach. Mini-mental state examination (MMSE) scores were used to assess cognitive impairment and were analyzed using an independent samples t-test.

Results

Compared with HCs, the VBM values in PATs were reduced in the left cerebellum and right thalamus but increased in the right brainstem, right precuneus and right paracentral lobule. The results of ROC curve analysis indicated that VBM may be useful in meibomian gland disease diagnosis. Comparison of MMSE scores between groups showed mild cognitive impairment in PATs.

Conclusion

PATs showed altered VBM values in some brain areas. These findings may provide information about the pathophysiology of meibomian gland dysfunction and may help to explain the underlying mechanisms of clinical manifestations in PATs, such as cognitive impairment. Abnormal VBM values in these brain areas may serve as predictive factors for development of meibomian gland disease in severely obese people and as indicators for individualized treatment.

The importance of the motor system in the development of music-based forms of auditory rehabilitation

Hearing abilities decline with age, and one of the most commonly reported hearing issues in older adults is a difficulty understanding speech when there is loud background noise. Understanding speech in noise relies on numerous cognitive processes, including working memory, and is supported by numerous brain regions, including the motor and motor planning systems. Indeed, many working memory processes are supported by motor and premotor cortical regions. Interestingly, lifelong musicians and nonmusicians given music training over the course of weeks or months show an improved ability to understand speech when there is loud background noise. These benefits are associated with enhanced working memory abilities, and enhanced activity in motor and premotor cortical regions. Accordingly, it is likely that music training improves the coupling between the auditory and motor systems and promotes plasticity in these regions and regions that feed into auditory/motor areas. This leads to an enhanced ability to dynamically process incoming acoustic information, and is likely the reason that musicians and those who receive laboratory-based music training are better able to understand speech when there is background noise. Critically, these findings suggest that music-based forms of auditory rehabilitation are possible and should focus on tasks that promote auditory-motor interactions.

Changes in cortical auditory evoked potentials in response to auditory training in elderly hearing aid users: A pilot study

OBJECTIVE

To compare the cortical auditory evoked potential responses pre-and post-Auditory Musical Training associated with hearing aid adaptation in elderly people with presbycusis.

DESIGN

This is a pilot, prospective, randomized, single-blind study.

STUDY SAMPLE

Eight presbiacusis elderly people between 65 and 80 years, new hearing aid users, divided into two groups participated in the study: Hearing Aid Group: use of hearing aid; and Auditory Training Group: use of hearing aid in addition to musical auditory training for 16 sessions. All participants were submitted to cortical auditory evoked potential tests with verbal stimulation in two different moments: Initial assessment, carried out before hearing aid adaptation and auditory training, and after three months, final assessment at the end of the auditory training sessions. All participants were adapted bilaterally with digital mini hearing aids.

RESULTS

There was a decrease in the P3a latency component for the Auditory Training Group when initial and final assessment were compared.

CONCLUSION

There was a change in the cortical auditory evoked potential in elderly people with presbycusis in response to the Musical Auditory Training associated with the use of hearing aids in elderly people with presbycusis.

The viability of the frequency following response characteristics for use as biomarkers of cognitive therapeutics in schizophrenia

Deficits in early auditory information processing contribute to cognitive and psychosocial disability; this has prompted development of interventions that target low-level auditory processing, which may alleviate these disabilities. The frequency following response (FFR) is a constellation of event-related potential and frequency characteristics that reflect the processing of acoustic stimuli at the level of the brainstem and ascending portions of the auditory pathway. While FFR is a promising candidate biomarker of response to auditory-based cognitive training interventions, the psychometric properties of FFR in schizophrenia patients have not been studied. Here we assessed the psychometric reliability and magnitude of group differences across 18 different FFR parameters to determine which of these parameters demonstrate adequate internal consistency. Electroencephalography from 40 schizophrenia patients and 40 nonpsychiatric comparison subjects was recorded during rapid presentation of an auditory speech stimulus (6000 trials). Patients showed normal response amplitudes but longer latencies for most FFR peaks and lower signal-to-noise ratios (SNRs) than healthy subjects. Analysis of amplitude and latency estimates of peaks, however, indicated a need for a substantial increase in task length to obtain internal consistency estimates above 0.80. In contrast, excellent internal consistency (>0.95) was shown for FFR sustained responses. Only SNR scores reflecting the FFR sustained response yielded significant group differences and excellent internal consistency, suggesting that this measure is a viable candidate for use in clinical treatment studies. The present study highlights the use of internal consistency estimates to select FFR characteristics for use in future intervention studies interested in individual differences among patients.

Categorical perception and influence of attention on neural consistency in response to speech sounds in adults with dyslexia

Developmental dyslexia is a common neurodevelopmental disorder that is associated with alterations in the behavioral and neural processing of speech sounds, but the scope and nature of that association is uncertain. It has been proposed that more variable auditory processing could underlie some of the core deficits in this disorder. In the current study, magnetoencephalography (MEG) data were acquired from adults with and without dyslexia while they passively listened to or actively categorized tokens from a /ba/-/da/ consonant continuum. We observed no significant group difference in active categorical perception of this continuum in either of our two behavioral assessments. During passive listening, adults with dyslexia exhibited neural responses that were as consistent as those of typically reading adults in six cortical regions associated with auditory perception, language, and reading. However, they exhibited significantly less consistency in the left supramarginal gyrus, where greater inconsistency correlated significantly with worse decoding skills in the group with dyslexia. The group difference in the left supramarginal gyrus was evident only when neural data were binned with a high temporal resolution and was only significant during the passive condition. Interestingly, consistency significantly improved in both groups during active categorization versus passive listening. These findings suggest that adults with dyslexia exhibit typical levels of neural consistency in response to speech sounds with the exception of the left supramarginal gyrus and that this consistency increases during active versus passive perception of speech sounds similarly in the two groups.

Bilinguals' speech perception in noise: Perceptual and neural associations

The current study characterized subcortical speech sound processing among monolinguals and bilinguals in quiet and challenging listening conditions and examined the relation between subcortical neural processing and perceptual performance. A total of 59 normal-hearing adults, ages 19–35 years, participated in the study: 29 native Hebrew-speaking monolinguals and 30 Arabic-Hebrew-speaking bilinguals. Auditory brainstem responses to speech sounds were collected in a quiet condition and with background noise. The perception of words and sentences in quiet and background noise conditions was also examined to assess perceptual performance and to evaluate the perceptual-physiological relationship. Perceptual performance was tested among bilinguals in both languages (first language (L1-Arabic) and second language (L2-Hebrew)). The outcomes were similar between monolingual and bilingual groups in quiet. Noise, as expected, resulted in deterioration in perceptual and neural responses, which was reflected in lower accuracy in perceptual tasks compared to quiet, and in more prolonged latencies and diminished neural responses. However, a mixed picture was observed among bilinguals in perceptual and physiological outcomes in noise. In the perceptual measures, bilinguals were significantly less accurate than their monolingual counterparts. However, in neural responses, bilinguals demonstrated earlier peak latencies compared to monolinguals. Our results also showed that perceptual performance in noise was related to subcortical resilience to the disruption caused by background noise. Specifically, in noise, increased brainstem resistance (i.e., fewer changes in the fundamental frequency (F0) representations or fewer shifts in the neural timing) was related to better speech perception among bilinguals. Better perception in L1 in noise was correlated with fewer changes in F0 representations, and more accurate perception in L2 was related to minor shifts in auditory neural timing. This study delves into the importance of using neural brainstem responses to speech sounds to differentiate individuals with different language histories and to explain inter-subject variability in bilinguals’ perceptual abilities in daily life situations.

Rapid Enhancement of Subcortical Neural Responses to Sine-Wave Speech

The efferent auditory nervous system may be a potent force in shaping how the brain responds to behaviorally significant sounds. Previous human experiments using the frequency following response (FFR) have shown efferent-induced modulation of subcortical auditory function online and over short- and long-term time scales; however, a contemporary understanding of FFR generation presents new questions about whether previous effects were constrained solely to the auditory subcortex. The present experiment used sine-wave speech (SWS), an acoustically-sparse stimulus in which dynamic pure tones represent speech formant contours, to evoke FFR_SWS. Due to the higher stimulus frequencies used in SWS, this approach biased neural responses toward brainstem generators and allowed for three stimuli (/bɔ/, /bu/, and /bo/) to be used to evoke FFR_SWSbefore and after listeners in a training group were made aware that they were hearing a degraded speech stimulus. All SWS stimuli were rapidly perceived as speech when presented with a SWS carrier phrase, and average token identification reached ceiling performance during a perceptual training phase. Compared to a control group which remained naïve throughout the experiment, training group FFR_SWS amplitudes were enhanced post-training for each stimulus. Further, linear support vector machine classification of training group FFR_SWS significantly improved post-training compared to the control group, indicating that training-induced neural enhancements were sufficient to bolster machine learning classification accuracy. These results suggest that the efferent auditory system may rapidly modulate auditory brainstem representation of sounds depending on their context and perception as non-speech or speech.

Evaluation of the frequency following response as a predictive biomarker of response to cognitive training in schizophrenia

Neurophysiological biomarkers of auditory processing show promise predicting outcomes following auditory-based targeted cognitive training (TCT) in schizophrenia, but the viability of the frequency following response (FFR) as a biomarker has yet to be examined, despite its ecological and face validity for auditory-based interventions. FFR is an event-related potential (ERP) that reflects early auditory processing. We predicted that schizophrenia patients would show acute- and longer-term FFR malleability in the context of TCT. Patients were randomized to either TCT (n = 30) or treatment as usual (TAU; n = 22), and electroencephalography was recorded during rapid presentation of an auditory speech stimulus before treatment, after one hour of training, and after 30 h of training. Whereas patients in the TCT group did not show changes in FFR after training, amplitude reductions were observed in the TAU. FFR was positively associated with performance on a measure of single word-in-noise perception in the TCT group, and with a measure of sentence-in-noise perception in both groups. Psychometric reliability analyses of FFR scores indicated high internal consistency but low one-hour and 12-week test-rest reliability. These findings support the dissociation between measures of speech discriminability along the hierarchy of cortical and subcortical early auditory information processing in schizophrenia.

A preliminary study on speech recognition in noise training for children with hearing loss

PURPOSE

The current study is a preliminary study to examine whether children with hearing loss would benefit from a speech recognition in noise training.

METHODS

Twenty-five children who wore hearing aids, cochlear implants, or bimodal devices from 4 to 12 years old participated in the study (experimental, n = 16; control, n = 9). The experimental group received a speech-in-noise training that took sixteen 15-min sessions spanning 8 to 12 weeks. The task involves recognizing monosyllabic target words and sentence keywords with various contextual cues in a multi-talker babble. The target stimuli were spoken by two females and fixed at 65 dB SPL throughout the training while the masker varied adaptively. Pre- and post-training tests measured the speech recognition thresholds of monosyllabic words and sentences spoken by two males in the babble noise. The test targets were presented at 55, 65, and 80 dB SPL.

RESULTS

The experimental group improved for word and sentence recognition in noise after training (Mean Difference = 2.4-2.5 dB, 2.7-4.2 dB, respectively). Training benefits were observed at trained (65 dB SPL) and untrained levels (55 and 80 dB SPL). The amount of post-training improvement was comparable between children using hearing aids and cochlear implants.

CONCLUSIONS

This preliminary study showed that children with hearing loss could benefit from a speech recognition in noise training that may fit into the children's school schedules. Training at a conversational level (65 dB SPL) transfers the benefit to levels 10-15 dB softer or louder. Training with female target talkers transfers the benefit to male target talkers. Overall, speech in noise training brings practical benefits for school-age children with hearing loss.

Non-stimulus-evoked activity as a measure of neural noise in the frequency-following response

BACKGROUND

The frequency-following response, or FFR, is a neurophysiologic response that captures distinct aspects of sound processing. Like all evoked responses, FFR is susceptible to electric and myogenic noise contamination during collection. Click-evoked auditory brainstem response collection standards have been adopted for FFR collection, however, whether these standards sufficiently limit FFR noise contamination is unknown. Thus, a critical question remains: to what extent do distinct FFR components reflect noise contamination? This is especially relevant for prestimulus amplitude (i.e., activity preceding the evoked response), as this measure has been used to index both noise contamination and neural noise.

NEW METHOD

We performed two experiments. First, using >1000 young-adult FFRs, we ran regressions to determine the variance explained by myogenic and electrical noise, as indexed by artifact rejection count and electrode impedance, on each FFR component. Second, we reanalyzed prestimulus amplitude differences attributed to athletic experience and socioeconomic status, adding covariates of artifact rejection and impedance.

RESULTS

We found that non-neural noise marginally contributed to FFR components and could not explain group differences on prestimulus amplitude.

COMPARISON WITH EXISTING METHOD

Prestimulus amplitude has been considered a measure of non-neural noise contamination. However, non-neural noise was not the sole contributor to variance in this measure and did not explain group differences.

CONCLUSIONS

Results from the two experiments suggest that the effects of non-neural noise on FFR components are minimal and do not obscure individual differences in the FFR and that prestimulus amplitude indexes neural noise.

Efficacy of Computer-Based Noise Desensitization Training in Children With Speech-in-Noise Deficits

Purpose Auditory training is known to improve the speech-perception-in-noise (SPIN) skills in children with auditory processing disorders (APDs); however, conventional non-computer-based trainings are dreary and nonmotivating. This study intended to develop a computer-based noise desensitization training module in Indian English and test the efficacy of the same in children with APD having SPIN deficits. There are no such modules available at present to be used in Indian children. Method The module incorporated words-in-noise training, with monosyllables and trisyllables as target words in the presence of speech-shaped noise as well as multitalker babble at different signal-to-noise ratios ranging from +20 to -4 dB SNR. The study included 20 children with SPIN deficits diagnosed with APD and who were recruited randomly to the experimental group who received the training (n = 10; M _age = 11.1 years) and to the control group who did not receive any training (n = 10; M _age = 11.4 years). The outcome measures included behavioral measures and electrophysiological measures (auditory long latency responses for speech in quiet and noise). Results Compared to children in the control group, children in the experimental group exhibited improvements in the SPIN scores as well as temporal processing measures after training. Dichotic consonant-vowel tests and auditory memory and sequencing tests did not yield significant improvement post training. Also, auditory long latency responses in quiet and noise revealed significant reduction in the amplitudes after training. No significant difference was noted in the latencies of auditory long latency responses post training. Control group participants did not show any significant difference in any of the measures between the initial and follow-up evaluations. Conclusions The developed training module was successful in fetching improvements in behavioral and electrophysiological measures. It would be a great addition to the evidence-based rehabilitation support inventory for children with SPIN deficits in India. Supplemental Material https://doi.org/10.23641/asha.14551041.

Dysfunction of the Auditory Brainstem as a Neurophysiology Subtype of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is very heterogeneous, particularly in language. Studies have suggested that language impairment is linked to auditory-brainstem dysfunction in ASD. However, not all ASD children have these deficits, which suggests potential subtypes of ASD. We classified ASD children into two subtypes according to their speech-evoked auditory brainstem response (speech-ABR) and explored the neural substrates for possible subtypes. Twenty-nine children with ASD and 25 typically developing (TD) peers were enrolled to undergo speech-ABR testing and structural magnetic resonance imaging (sMRI). There were significant differences between the ASD group and TD group in surface area, cortical volume and cortical thickness. According to speech-ABR results, ASD participants were divided into the ASD-typical (ASD-T) group and ASD-atypical (ASD-A) group. Compared with the ASD-T group, the ASD-A group had a lower score in language of the Gesell Developmental Diagnosis Scale (GDDS), increased left rostral middle frontal gyrus (lRMFG) area and decreased local gyrification index of the right superior temporal gyrus. GDDS-language and surface area of lRMFG were correlated to the wave-A amplitude in ASD. Surface area of lRMFG had an indirect effect on language performance via alteration of the wave-V amplitude. Thus, cortical deficits may impair language ability in children with ASD by causing subcortical dysfunction at preschool age. These evidences support dysfunction of the auditory brainstem as a potential subtype of ASD. Besides, this subtype-based method may be useful for various clinical applications.

Hearing and dementia: from ears to brain

The association between hearing impairment and dementia has emerged as a major public health challenge, with significant opportunities for earlier diagnosis, treatment and prevention. However, the nature of this association has not been defined. We hear with our brains, particularly within the complex soundscapes of everyday life: neurodegenerative pathologies target the auditory brain, and are therefore predicted to damage hearing function early and profoundly. Here we present evidence for this proposition, based on structural and functional features of auditory brain organization that confer vulnerability to neurodegeneration, the extensive, reciprocal interplay between 'peripheral' and 'central' hearing dysfunction, and recently characterized auditory signatures of canonical neurodegenerative dementias (Alzheimer's disease, Lewy body disease and frontotemporal dementia). Moving beyond any simple dichotomy of ear and brain, we argue for a reappraisal of the role of auditory cognitive dysfunction and the critical coupling of brain to peripheral organs of hearing in the dementias. We call for a clinical assessment of real-world hearing in these diseases that moves beyond pure tone perception to the development of novel auditory 'cognitive stress tests' and proximity markers for the early diagnosis of dementia and management strategies that harness retained auditory plasticity.

Neural generators of the frequency-following response elicited to stimuli of low and high frequency: A magnetoencephalographic (MEG) study

The frequency-following response (FFR) to periodic complex sounds has gained recent interest in auditory cognitive neuroscience as it captures with great fidelity the tracking accuracy of the periodic sound features in the ascending auditory system. Seminal studies suggested the FFR as a correlate of subcortical sound encoding, yet recent studies aiming to locate its sources challenged this assumption, demonstrating that FFR receives some contribution from the auditory cortex. Based on frequency-specific phase-locking capabilities along the auditory hierarchy, we hypothesized that FFRs to higher frequencies would receive less cortical contribution than those to lower frequencies, hence supporting a major subcortical involvement for these high frequency sounds. Here, we used a magnetoencephalographic (MEG) approach to trace the neural sources of the FFR elicited in healthy adults (N = 19) to low (89 Hz) and high (333 Hz) frequency sounds. FFRs elicited to the high and low frequency sounds were clearly observable on MEG and comparable to those obtained in simultaneous electroencephalographic recordings. Distributed source modeling analyses revealed midbrain, thalamic, and cortical contributions to FFR, arranged in frequency-specific configurations. Our results showed that the main contribution to the high-frequency sound FFR originated in the inferior colliculus and the medial geniculate body of the thalamus, with no significant cortical contribution. In contrast, the low-frequency sound FFR had a major contribution located in the auditory cortices, and also received contributions originating in the midbrain and thalamic structures. These findings support the multiple generator hypothesis of the FFR and are relevant for our understanding of the neural encoding of sounds along the auditory hierarchy, suggesting a hierarchical organization of periodicity encoding.

Acoustically Controlled Binaural Auditory Training with Vocal Duets: Assessment and Effectiveness

OBJECTIVES

We aimed to evaluate the effectiveness of a binaural auditory training program with vocal duets by comparing skills through outcomes from behavioral and electrophysiological assessment instruments at three moments: before the intervention, moment one (M1); immediately after training, moment two (M2); and 3 months after, moment three (M3).

METHODS

This interventional, longitudinal, prospective, and uncontrolled study was approved by our Research Ethics Committee. Binaural auditory training with vocal duets (ATVD) was applied in 10 adults with normal audiometric thresholds and auditory processing disorders. ATVD used four different vocals of a public domain song sung in a cappella as stimuli. Participants were asked to register any perceived difference in frequency for each syllable of the song during 30-minute sessions twice a week. The number of sessions required ranged from 12 (6 hours) to 20 (10 hours).

RESULTS

Regarding behavioral tests, the dichotic consonant-vowel test showed significant evidence of an improved advantage in the left ear (LE) in the non-forced condition and a significant reduction in the number of errors at M2 and M3 in the forced left condition. The speech-in-noise test and frequency pattern test showed a significant reduction in impaired results at M2 and M3. Electrophysiological results showed a significant increase in the LE amplitude in the P3 long-latency auditory evoked potentials test, as well as a decrease in the auditory brainstem response test (III-V and I-V inter-peak latencies in the right ear and wave I and I-III inter-peak latencies in LE).

CONCLUSION

The effectiveness of ATVD was evidenced, and the results were maintained after 3 months.

Factors influencing classification of frequency following responses to speech and music stimuli

Successful mapping of meaningful labels to sound input requires accurate representation of that sound's acoustic variances in time and spectrum. For some individuals, such as children or those with hearing loss, having an objective measure of the integrity of this representation could be useful. Classification is a promising machine learning approach which can be used to objectively predict a stimulus label from the brain response. This approach has been previously used with auditory evoked potentials (AEP) such as the frequency following response (FFR), but a number of key issues remain unresolved before classification can be translated into clinical practice. Specifically, past efforts at FFR classification have used data from a given subject for both training and testing the classifier. It is also unclear which components of the FFR elicit optimal classification accuracy. To address these issues, we recorded FFRs from 13 adults with normal hearing in response to speech and music stimuli. We compared labeling accuracy of two cross-validation classification approaches using FFR data: (1) a more traditional method combining subject data in both the training and testing set, and (2) a "leave-one-out" approach, in which subject data is classified based on a model built exclusively from the data of other individuals. We also examined classification accuracy on decomposed and time-segmented FFRs. Our results indicate that the accuracy of leave-one-subject-out cross validation approaches that obtained in the more conventional cross-validation classifications while allowing a subject's results to be analysed with respect to normative data pooled from a separate population. In addition, we demonstrate that classification accuracy is highest when the entire FFR is used to train the classifier. Taken together, these efforts contribute key steps toward translation of classification-based machine learning approaches into clinical practice.

Learning a Second Language in Adulthood Changes Subcortical Neural Encoding

Second language learning has been shown to impact and reshape the central nervous system, anatomically and functionally. Most of the studies on second language learning and neuroplasticity have been focused on cortical areas, whereas the subcortical neural encoding mechanism and its relationship with L2 learning have not been examined extensively. The purpose of this study was to utilize frequency-following response (FFR) to examine if and how learning a tonal language in adulthood changes the subcortical neural encoding in hearing adults. Three groups of subjects were recruited: native speakers of Mandarin Chinese (native speakers (NS)), learners of the language (L2 learners), and those with no experience (native speakers of foreign languages (NSFL)). It is hypothesized that differences would exist in FFRs obtained from the three language experience groups. Results revealed that FFRs obtained from L2 learners were found to be more robust than the NSFL group, yet not on a par with the NS group. Such results may suggest that in human adulthood, subcortical neural encoding ability may be trainable with the acquisition of a new language and that neuroplasticity at the brainstem level can indeed be influenced by L2 learning.

Effect of Vowel Auditory Training on the Speech-In-Noise Perception among Older Adults with Normal Hearing

Introduction:

Aging reduces the ability to understand speech in noise. Hearing rehabilitation is one of the ways to help older people communicate effectively. This study aimed to investigate the effect of vowel auditory training on the improvement of speech-in-noise (SIN) perception among elderly listeners.

Materials and Methods:

This study was conducted on 36 elderly listeners (17 males and 15 females) with the mean±SD of 67.6±6.33. They had the normal peripheral auditory ability but had difficulties in SIN perception. The samples were randomly divided into two groups of intervention and control. The intervention group underwent vowel auditory training; however, the control group received no training.

Results:

After vowel auditory training, the intervention group showed significant changes in the results of the SIN test at two signal-to-noise ratios of 0 and -10 and the Iranian version of the Speech, Spatial, and Qualities of Hearing Scale, compared to the control group (P<0.001). Regarding the Speech Auditory Brainstem Response test, the F₀ magnitude was higher in the intervention group (8.42±2.26), compared to the control group (6.68±1.87) (P<0.011).

Conclusion:

This study investigated the effect of vowel auditory training on the improvement of SIN perception which could be probably due to better F₀ encoding and receiving. This ability enhancement resulted in the easier perception of speech and its more proper separation from background noise which in turn enhanced the ability of the old people to follow the speech of a specific person and track the discussion.

The effects of a temporal processing-based auditory training program on the auditory skills of elderly users of hearing aids: a study protocol for a randomized clinical trial

Background: One of the most important effects of age-related declines in neural processing speed is the impairment of temporal resolution, which leads to difficulty hearing in noisy environments. Since the central auditory system is highly plastic, by designing and implementing a temporal processing-based auditory training program, we can help the elderly improve their listening skills and speech understanding in noisy environments.

Methods: In the first phase of this research, based on the theoretical framework of temporal processing, an auditory training solution was developed as a software program. In the second phase, which will be described in the present study, the effects of the designed program on the listening skills of the elderly users of hearing aids (age: 60-75 years) will be studied in the control and intervention groups. In the intervention group, the auditory training program will be implemented for three months (36 sessions), and the results of central tests (GIN, DPT, QuickSIN) and the electrophysiological speech-ABR test will be compared in both groups before, immediately and one month after the intervention.

Discussion: Since temporal processing is not sufficient in auditory training programs for the elderly with hearing impairments, implementation of a temporal processing-based auditory training program can reduce hearing problems in noisy environments among elderly users of hearing aids.

Trial registration: This study was registered as a clinical trial in the Iranian Registry of Clinical Trials ( IRCT20190921044838N1) on December 25, 2019.

Noise-Induced Changes of the Auditory Brainstem Response to Speech-a Measure of Neural Desynchronisation?

It is commonly assumed that difficulty in listening to speech in noise is at least partly due to deficits in neural temporal processing. Given that noise reduces the temporal fidelity of the auditory brainstem response (ABR) to speech, it has been suggested that the speech ABR may serve as an index of such neural deficits. However, the temporal fidelity of ABRs, to both speech and non-speech sounds, is also known to be influenced by the cochlear origin of the response, as responses from higher-frequency cochlear regions are faster and more synchronous than responses from lower-frequency regions. Thus, if noise caused a reweighting of response contributions from higher- to lower-frequency cochlear regions, the temporal fidelity of the aggregate response should be reduced even in the absence of any changes in neural processing. This ‘place mechanism’ has been demonstrated for non-speech ABRs. The aim of this study was to test whether it also applies to speech ABRs. We used the so-called ‘derived-band’ method to isolate response contributions from frequency-limited cochlear regions. Broadband and derived-band speech ABRs were measured both in quiet and in noise. Whilst the noise caused significant changes to the temporal properties of the broadband response, its effects on the derived-band responses were mostly restricted to the response amplitudes. Importantly, the amplitudes of the higher-frequency derived-band responses were much more strongly affected than those of the lower-frequency responses, suggesting that the noise indeed caused a reweighting effect. Our results indicate that, as for non-speech ABRs, the cochlear place mechanism can represent a potentially substantial confound to speech-ABR-in-noise measurements.

Short-Term Choir Singing Supports Speech-in-Noise Perception and Neural Pitch Strength in Older Adults With Age-Related Hearing Loss

Prior studies have demonstrated musicianship enhancements of various aspects of auditory and cognitive processing in older adults, but musical training has rarely been examined as an intervention for mitigating age-related declines in these abilities. The current study investigates whether 10 weeks of choir participation can improve aspects of auditory processing in older adults, particularly speech-in-noise (SIN) perception. A choir-singing group and an age- and audiometrically-matched do-nothing control group underwent pre- and post-testing over a 10-week period. Linear mixed effects modeling in a regression analysis showed that choir participants demonstrated improvements in speech-in-noise perception, pitch discrimination ability, and the strength of the neural representation of speech fundamental frequency. Choir participants' gains in SIN perception were mediated by improvements in pitch discrimination, which was in turn predicted by the strength of the neural representation of speech stimuli (FFR), suggesting improvements in pitch processing as a possible mechanism for this SIN perceptual improvement. These findings support the hypothesis that short-term choir participation is an effective intervention for mitigating age-related hearing losses.

Stable auditory processing underlies phonological awareness in typically developing preschoolers

Sound processing is an important scaffold for early language acquisition. Here we investigate its relationship to three components of phonological processing in young children (∼age 3): Phonological Awareness (PA), Phonological Memory (PM), and Rapid Automatized Naming (RAN). While PA is believed to hinge upon consistency of sound processing to distinguish and manipulate word features, PM relies on an internal store of the sounds of language and RAN relies on fluid production of those sounds. Given the previously demonstrated link between PA and the auditory system, we hypothesized that only this component would be associated with auditory neural stability. Moreover, we expected relationships to manifest at early ages because additional factors may temper the association in older children. We measured across-trial stability of the frequency-following response, PA, PM, and RAN longitudinally in twenty-seven children. Auditory neural stability at age ∼3 years exclusively predicts PA, but this relationship vanishes in older children.

Auditory Stimulation Training With Technically Manipulated Musical Material in Preschool Children With Specific Language Impairments: An Explorative Study

Auditory stimulation training (AST) has been proposed as a potential treatment for children with specific language impairments (SLI). The current study was designed to test this assumption by using an AST with technically modulated musical material (ASTM) in a randomized control group design. A total of 101 preschool children (62 male, 39 females; mean age = 4.52 years, SD = 0.62) with deficits in speech comprehension and poor working memory capacity were randomly allocated into one of two treatment groups or a control group. Children in the ASTM group (n = 40) received three 30-min sessions per week over 12 weeks, whereas children in the comparison group received pedagogical activities during these intervals (n = 24). Children in the control group (n = 37) received no treatment. Working memory, phoneme discrimination and speech perception skills were tested prior to (baseline) and after treatment. Children in the ASTM group showed significantly greater working memory capacity, speech perception, and phoneme discrimination skills after treatment, whereas children in the other groups did not show such improvement. Taken together, these results suggest that ASTM can enhance auditory cognitive performance in children with SLI.

[Efficacy of Music Therapy in Functional Recovery of the Upper Limb After a Stroke: a Systematic Review and Meta-Analysis]

INTRODUCTION

Formal therapeutic interventions based on music have been used in rehabilitation to stimulate the brain functions involved in movement.

OBJECTIVE

The objective of this study was to conduct a systematic review and meta-analysis following the PRISMA recommendations on the effectiveness of music therapy in improving the functionality of the upper limb in patients with hemiparesis secondary to stroke.

METHODS

A search of the Pubmed, clinicaltrials.gov and Cochrane databases was performed in September 2018. The articles included in this review had to meet the following criteria: randomised controlled trials with therapeutic interventions that evaluated improvement in manual dexterity, measured with the box and block test in patients older than 18 years with a residual deficit secondary to an ischaemic or haemorrhagic stroke in the previous months.

RESULTS

Of 371 studies analysed, six were included in the study and subsequent meta-analysis with a total of 149 patients. The musical interventions improved the functionality of the parietal limb in patients with stroke compared with that in controls who received conventional treatment. This effect was statistically significant in the meta-analysis, with a difference in the standardised mean in the box and block test of 0.40 (95% CI 0.09 - 0.72).

CONCLUSIONS

Musical interventions could be beneficial for the functional recovery of the upper extremity. These results are encouraging but a greater number of clinical trials are required to confirm these findings before their subsequent implementation in clinical practice.

Human Frequency Following Responses to Vocoded Speech: Amplitude Modulation Versus Amplitude Plus Frequency Modulation

OBJECTIVES

The most commonly employed speech processing strategies in cochlear implants (CIs) only extract and encode amplitude modulation (AM) in a limited number of frequency channels. proposed a novel speech processing strategy that encodes both frequency modulation (FM) and AM to improve CI performance. Using behavioral tests, they reported better speech, speaker, and tone recognition with this novel strategy than with the AM-alone strategy. Here, we used the scalp-recorded human frequency following responses (FFRs) to examine the differences in the neural representation of vocoded speech sounds with AM alone and AM + FM as the spectral and temporal cues were varied. Specifically, we were interested in determining whether the addition of FM to AM improved the neural representation of envelope periodicity (FFRENV) and temporal fine structure (FFRTFS), as reflected in the temporal pattern of the phase-locked neural activity generating the FFR.

DESIGN

FFRs were recorded from 13 normal-hearing, adult listeners in response to the original unprocessed stimulus (a synthetic diphthong /au/ with a 110-Hz fundamental frequency or F0 and a 250-msec duration) and the 2-, 4-, 8- and 16-channel sine vocoded versions of /au/ with AM alone and AM + FM. Temporal waveforms, autocorrelation analyses, fast Fourier Transform, and stimulus-response spectral correlations were used to analyze both the strength and fidelity of the neural representation of envelope periodicity (F0) and TFS (formant structure).

RESULTS

The periodicity strength in the FFRENV decreased more for the AM stimuli than for the relatively resilient AM + FM stimuli as the number of channels was increased. Regardless of the number of channels, a clear spectral peak of FFRENV was consistently observed at the stimulus F0 for all the AM + FM stimuli but not for the AM stimuli. Neural representation as revealed by the spectral correlation of FFRTFS was better for the AM + FM stimuli when compared to the AM stimuli. Neural representation of the time-varying formant-related harmonics as revealed by the spectral correlation was also better for the AM + FM stimuli as compared to the AM stimuli.

CONCLUSIONS

These results are consistent with previously reported behavioral results and suggest that the AM + FM processing strategy elicited brainstem neural activity that better preserved periodicity, temporal fine structure, and time-varying spectral information than the AM processing strategy. The relatively more robust neural representation of AM + FM stimuli observed here likely contributes to the superior performance on speech, speaker, and tone recognition with the AM + FM processing strategy. Taken together, these results suggest that neural information preserved in the FFR may be used to evaluate signal processing strategies considered for CIs.

Auditory rehabilitation in adults: results of a training program

ABSTRACT Objective: to describe the findings of the auditory processing behavioral tests in patients with hearing loss before and after hearing aid fitting associated with auditory training. Methods: a descriptive analytical study that compared the findings of the auditory processing evaluation in 22 patients, from 19 to 62 years old, with mild or moderate sensorineural hearing loss. Tests used: Sound localization; Masking Level Difference; Alternate Disyllables Dichotic Listening Test; Melodic Frequency Pattern Test, Melodic Duration Pattern Test; Gaps in Noise; Speech in Noise Test. After the first tests, the patients were fitted with hearing aids and underwent eight auditory training sessions. The tests were retaken after a two-month period. Results: there was a predominance of females and a moderate degree hearing loss. In the comparison of the initial and final assessment situations, a statistically significant difference (p <0.05) was seen in all conditions studied, except for the Gaps in Noise and Masking Level Difference tests. Conclusion: the results have proven that the auditory training performed in adult users of hearing aids brought about significant improvements on the auditory processing skills, thus, modifying their auditory behavior. The improvement of the results of the auditory processing behavioral tests in the initial and final situations reflects the hearing functional improvement achieved.

Inter-modality influence on the brainstem using an arithmetic exercise

This study investigates the inter-modality influence on the brainstem using a mental task (arithmetic exercise). Frequency Following Responses were recorded in quiet and noise, across four stimuli conditions (No Task, Easy, Medium, and Difficult). For the No Task, subjects were instructed to direct their attention to the presented speech vowel while no mental task was performed. For the Easy, Medium, and Difficult conditions, subjects were instructed to direct their attention to the mental task while ignoring simultaneously presented speech vowel /a/. Results from this study suggest that top-down influences such as selective attention and working memory have no significant effects at the level of the brainstem in both listening backgrounds (quiet and noise).

Brainstem Evoked Potential Indices of Subcortical Auditory Processing After Mild Traumatic Brain Injury

OBJECTIVES

The primary aim of this study was to assess subcortical auditory processing in individuals with chronic symptoms after mild traumatic brain injury (mTBI) by measuring auditory brainstem responses (ABRs) to standard click and complex speech stimuli. Consistent with reports in the literature of auditory problems after mTBI (despite normal-hearing thresholds), it was hypothesized that individuals with mTBI would have evidence of impaired neural encoding in the auditory brainstem compared to noninjured controls, as evidenced by delayed latencies and reduced amplitudes of ABR components. We further hypothesized that the speech-evoked ABR would be more sensitive than the click-evoked ABR to group differences because of its complex nature, particularly when recorded in a background noise condition.

DESIGN

Click- and speech-ABRs were collected in 32 individuals diagnosed with mTBI in the past 3 to 18 months. All mTBI participants were experiencing ongoing injury symptoms for which they were seeking rehabilitation through a brain injury rehabilitation management program. The same data were collected in a group of 32 age- and gender-matched controls with no history of head injury. ABRs were recorded in both left and right ears for all participants in all conditions. Speech-ABRs were collected in both quiet and in a background of continuous 20-talker babble ipsilateral noise. Peak latencies and amplitudes were compared between groups and across subgroups of mTBI participants categorized by their behavioral auditory test performance.

RESULTS

Click-ABR results were not significantly different between the mTBI and control groups. However, when comparing the control group to only those mTBI subjects with measurably decreased performance on auditory behavioral tests, small differences emerged, including delayed latencies for waves I, III, and V. Similarly, few significant group differences were observed for peak amplitudes and latencies of the speech-ABR when comparing at the whole group level but were again observed between controls and those mTBI subjects with abnormal behavioral auditory test performance. These differences were seen for the onset portions of the speech-ABR waveforms in quiet and were close to significant for the onset wave. Across groups, quiet versus noise comparisons were significant for most speech-ABR measures but the noise condition did not reveal more group differences than speech-ABR in quiet, likely because of variability and overall small amplitudes in this condition for both groups.

CONCLUSIONS

The outcomes of this study indicate that subcortical neural encoding of auditory information is affected in a significant portion of individuals with long-term problems after mTBI. These subcortical differences appear to relate to performance on tests of auditory processing and perception, even in the absence of significant hearing loss on the audiogram. While confounds of age and slight differences in audiometric thresholds cannot be ruled out, these preliminary results are consistent with the idea that mTBI can result in neuronal changes within the subcortical auditory pathway that appear to relate to functional auditory outcomes. Although further research is needed, clinical audiological evaluation of individuals with ongoing post-mTBI symptoms is warranted for identification of individuals who may benefit from auditory rehabilitation as part of their overall treatment plan.

Home-based hand rehabilitation after chronic stroke: Randomized, controlled single-blind trial comparing the MusicGlove with a conventional exercise program

Individuals with chronic stroke have limited options for hand rehabilitation at home. Here, we sought to determine the feasibility and efficacy of home-based MusicGlove therapy. Seventeen participants with moderate hand impairment in the chronic phase of stroke were randomized to 3 wk of home-based exercise with either the MusicGlove or conventional tabletop exercises. The primary outcome measure was the change in the Box and Blocks test score from baseline to 1 mo posttreatment. Both groups significantly improved their Box and Blocks test score, but no significant difference was found between groups. The MusicGlove group did exhibit significantly greater improvements than the conventional exercise group in motor activity log quality of movement and amount of use scores 1 mo posttherapy (p = 0.007 and p = 0.04, respectively). Participants significantly increased their use of MusicGlove over time, completing 466 gripping movements per day on average at study end. MusicGlove therapy was not superior to conventional tabletop exercises for the primary end point but was nevertheless feasible and led to a significantly greater increase in self-reported functional use and quality of movement of the impaired hand than conventional home exercises.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; "Influence of Timing on Motor Learning"; NCT01769326; https://clinicaltrials.gov/ct2/show/NCT01769326.

Behavioral and subcortical signatures of musical expertise in Mandarin Chinese speakers

Both musical training and native language have been shown to have experience-based plastic effects on auditory processing. However, the combined effects within individuals are unclear. Recent research suggests that musical training and tone language speaking are not clearly additive in their effects on processing of auditory features and that there may be a disconnect between perceptual and neural signatures of auditory feature processing. The literature has only recently begun to investigate the effects of musical expertise on basic auditory processing for different linguistic groups. This work provides a profile of primary auditory feature discrimination for Mandarin speaking musicians and nonmusicians. The musicians showed enhanced perceptual discrimination for both frequency and duration as well as enhanced duration discrimination in a multifeature discrimination task, compared to nonmusicians. However, there were no differences between the groups in duration processing of nonspeech sounds at a subcortical level or in subcortical frequency representation of a nonnative tone contour, for f_o or for the first or second formant region. The results indicate that musical expertise provides a cognitive, but not subcortical, advantage in a population of Mandarin speakers.

Construction of an Arabic computerized battery for cognitive rehabilitation of children with specific learning disabilities

PURPOSE

The aim of this study was to design an Arabic computerized battery of cognitive skills for training children with specific learning disabilities (SLD).

SUBJECTS AND METHODS

Nineteen students from fourth grade primary schools in Assiut, Egypt, who were previously diagnosed with SLD, agreed to participate in the rehabilitation program. The study passed through four stages: first stage, detailed analysis of the cognitive profile of students with SLD (n=19), using a previously constructed diagnostic cognitive skill battery, to identify deficits in their cognitive skills; second stage, construction of an Arabic computerized battery for cognitive training of students with SLD; third stage, implementation of the constructed training program for the students, each tailored according to his/her previously diagnosed cognitive skill deficit/deficits; and fourth stage, post-training re-evaluation of academic achievement and cognitive skills' performance.

RESULTS

Students with SLD have a wide range of cognitive skill deficits, which are more frequent in auditory cognitive skills (68.4%) than in visual cognitive skills (64.1%), particularly in phonological awareness and auditory sequential memory (78.9%). Following implementation of the training program, there was a statistically significant increase (P<0.001) in the mean scores of total auditory and visual cognitive skills, as well as in academic achievement (P<0.001) of the study group.

CONCLUSION

Remediation-oriented diagnosis of cognitive skills, when tailored according to previously diagnosed cognitive deficits, leads to the improvement in learning abilities and academic achievement of students with SLD.

Oculomotor rehabilitation in children with dyslexia

Background: Dyslexia is the most common learning disorder. Visual and oculomotor deficits in dyslexic children have been reported. The purpose of this study was to measure oculomotor parameters and analyze the effect of oculomotor rehabilitation strategies on dyslexia. Methods: Binocular eye movements were recorded by oculomotor subtype of videonystagmography (VNG) testing on 30 children with dyslexia and 20 typical reader children (aged 8-12) in both genders. Dyslexic children were diagnosed with DSM-V scale by experts in reading disorder centers. We studied those children with developmental dyslexia, who had deficits in eye movements recording. Dyslexic children were divided into 2 groups of case and control. Oculomotor rehabilitation (including fixation, saccade, and tracking training) was performed in case group for 1 hour, twice weekly for 8 weeks. Before the intervention, results of oculomotor tests were compared between 3 groups (healthy, case, and control). Then, to analyze the effect of the intervention, results of oculomotor tests were compared between case and control groups in pre- and post- intervention stage. Data were analyzed by independent and paired samples t tests, ANOVA, and repeated measures tests in SPSS v. 21. Results: There were significant differences in oculomotor characteristics of dyslexic children in comparison with those reported in typical children. Oculomotor rehabilitation intervention had a positive effect on improvement of oculomotor responses and eye movements in dyslexic children. Moreover, there was no statistically significant difference between dyslexic children and non-dyslexic children in oculomotor skills after the training. Conclusion: Our results showed the positive effects of oculomotor rehabilitation on eye movements. Primary oculomotor assessment in dyslexic children and early use of oculomotor rehabilitation combined with other treatments are highly recommended.

Monkeys share the neurophysiological basis for encoding sound periodicities captured by the frequency-following response with humans

The extraction and encoding of acoustical temporal regularities are fundamental for human cognitive auditory abilities such as speech or beat entrainment. Because the comparison of the neural sensitivity to temporal regularities between human and animals is fundamental to relate non-invasive measures of auditory processing to their neuronal basis, here we compared the neural representation of auditory periodicities between human and non-human primates by measuring scalp-recorded frequency-following response (FFR). We found that rhesus monkeys can resolve the spectrotemporal structure of periodic stimuli to a similar extent as humans by exhibiting a homologous FFR potential to the speech syllable /da/. The FFR in both species is robust and phase-locked to the fundamental frequency of the sound, reflecting an effective neural processing of the fast-periodic information of subsyllabic cues. Our results thus reveal a conserved neural ability to track acoustical regularities within the primate order. These findings open the possibility to study the neurophysiology of complex sound temporal processing in the macaque subcortical and cortical areas, as well as the associated experience-dependent plasticity across the auditory pathway in behaving monkeys.

Differences between auditory frequency-following responses and onset responses: Intracranial evidence from rat inferior colliculus

A periodic sound, such as a pure tone, evokes both transient onset field-potential responses and sustained frequency-following responses (FFRs) in the auditory midbrain, the inferior colliculus (IC). It is not clear whether the two types of responses are based on the same or different neural substrates. Although it has been assumed that FFRs are based on phase locking to the periodic sound, the evidence showing the direct relationship between the FFR amplitude and the phase-locking strength is still lacking. Using intracranial recordings from the rat central nucleus of inferior colliculus (ICC), this study was to examine whether FFRs and onset responses are different in sensitivity to pure-tone frequency and/or response-stimulus correlation, when a tone stimulus is presented either monaurally or binaurally. Particularly, this study was to examine whether the FFR amplitude is correlated with the strength of phase locking. The results showed that with the increase of tone-stimulus frequency from 1 to 2 kHz, the FFR amplitude decreased but the onset-response amplitude increased. Moreover, the FFR amplitude, but not the onset-response amplitude, was significantly correlated with the phase coherence between tone-evoked potentials and the tone stimulus. Finally, the FFR amplitude was negatively correlated with the onset-response amplitude. These results indicate that periodic-sound-evoked FFRs are based on phase-locking activities of sustained-response neurons, but onset responses are based on transient activities of onset-response neurons, suggesting that FFRs and onset responses are associated with different functions.

Human Brainstem Exhibits higher Sensitivity and Specificity than Auditory-Related Cortex to Short-Term Phonetic Discrimination Learning

Phonetic discrimination learning is an active perceptual process that operates under the influence of cognitive control mechanisms by increasing the sensitivity of the auditory system to the trained stimulus attributes. It is assumed that the auditory cortex and the brainstem interact in order to refine how sounds are transcribed into neural codes. Here, we evaluated whether these two computational entities are prone to short-term functional changes, whether there is a chronological difference in malleability, and whether short-term training suffices to alter reciprocal interactions. We performed repeated cortical (i.e., mismatch negativity responses, MMN) and subcortical (i.e., frequency-following response, FFR) EEG measurements in two groups of participants who underwent one hour of phonetic discrimination training or were passively exposed to the same stimulus material. The training group showed a distinctive brainstem energy reduction in the trained frequency-range (i.e., first formant), whereas the passive group did not show any response modulation. Notably, brainstem signal change correlated with the behavioral improvement during training, this result indicating a close relationship between behavior and underlying brainstem physiology. Since we did not reveal group differences in MMN responses, results point to specific short-term brainstem changes that precede functional alterations in the auditory cortex.

Practical guidelines to minimise language and cognitive confounds in the diagnosis of CAPD: a brief tutorial

OBJECTIVE

To provide audiologists with strategies to minimise confounding cognitive and language processing variables and accurately diagnose central auditory processing disorder (CAPD).

DESIGN

Tutorial.

STUDY SAMPLE

None.

RESULTS

Strategies are reviewed to minimise confounding cognitive and language processing variables and accurately diagnose CAPD.

CONCLUSIONS

Differential diagnosis is exceedingly important and can be quite challenging. Distinguishing between two or more conditions presenting with similar symptoms or attributes requires multidisciplinary, comprehensive assessment. To ensure appropriate interventions, the audiologist is a member of the multidisciplinary team responsible for determining whether there is an auditory component to other presenting deficits or whether one condition is responsible for the symptoms seen in another. Choice of tests should be guided both by the symptoms of the affected individual, as established in an in-depth interview and case history, the individual's age and primary language, and by the specific deficits reported to be associated with specific clinical presentations. Knowing which tests are available, their strengths and limitations, the processes assessed, task and response requirements, and the areas of the central auditory nervous system (CANS) to which each test is most sensitive provides the audiologist with critical information to assist in the differential diagnostic process.