Speech recognition and temporal processing in middle-aged women

Aging effects on the neural representation and perception of consonant transition cues

Older listeners have difficulty processing temporal cues that are important for word discrimination, and deficient processing may limit their ability to benefit from these cues. Here, we investigated aging effects on perception and neural representation of the consonant transition and the factors that contribute to successful perception. To further understand the neural mechanisms underlying the changes in processing from brainstem to cortex, we also examined the factors that contribute to exaggerated amplitudes in cortex. We enrolled 30 younger normal-hearing and 30 older normal-hearing participants who met the criteria of clinically normal hearing. Perceptual identification functions were obtained for the words BEAT and WHEAT on a 7-step continuum of consonant-transition duration. Auditory brainstem responses (ABRs) were recorded to click stimuli and frequency-following responses (FFRs) and cortical auditory-evoked potentials were recorded to the endpoints of the BEAT-WHEAT continuum. Perceptual performance for identification of BEAT vs. WHEAT did not differ between younger and older listeners. However, both subcortical and cortical measures of neural representation showed age group differences, such that FFR phase locking was lower but cortical amplitudes (P1 and N1) were higher in older compared to younger listeners. ABR Wave I amplitude and FFR phase locking, but not audiometric thresholds, predicted early cortical amplitudes. Phase locking to the transition region and early cortical peak amplitudes (P1) predicted performance on the perceptual identification function. Overall, results suggest that the neural representation of transition durations and cortical overcompensation may contribute to the ability to perceive transition duration contrasts. Cortical overcompensation appears to be a maladaptive response to decreased neural firing/synchrony.

Acute Aromatase Inhibition Impairs Neural and Behavioral Auditory Scene Analysis in Zebra Finches

Auditory perception can be significantly disrupted by noise. To discriminate sounds from noise, auditory scene analysis (ASA) extracts the functionally relevant sounds from acoustic input. The zebra finch communicates in noisy environments. Neurons in their secondary auditory pallial cortex (caudomedial nidopallium, NCM) can encode song from background chorus, or scenes, and this capacity may aid behavioral ASA. Furthermore, song processing is modulated by the rapid synthesis of neuroestrogens when hearing conspecific song. To examine whether neuroestrogens support neural and behavioral ASA in both sexes, we retrodialyzed fadrozole (aromatase inhibitor, FAD) and recorded in vivo awake extracellular NCM responses to songs and scenes. We found that FAD affected neural encoding of songs by decreasing responsiveness and timing reliability in inhibitory (narrow-spiking), but not in excitatory (broad-spiking) neurons. Congruently, FAD decreased neural encoding of songs in scenes for both cell types, particularly in females. Behaviorally, we trained birds using operant conditioning and tested their ability to detect songs in scenes after administering FAD orally or injected bilaterally into NCM. Oral FAD increased response bias and decreased correct rejections in females, but not in males. FAD in NCM did not affect performance. Thus, FAD in the NCM impaired neuronal ASA but that did not lead to behavioral disruption suggesting the existence of resilience or compensatory responses. Moreover, impaired performance after systemic FAD suggests involvement of other aromatase-rich networks outside the auditory pathway in ASA. This work highlights how transient estrogen synthesis disruption can modulate higher-order processing in an animal model of vocal communication.

Preserved Gray Matter Volume in the Left Superior Temporal Gyrus Underpins Speech-in-Noise Processing in Middle-Aged Adults

BACKGROUND

Neuroanatomical evidence suggests that behavioral speech-in-noise (SiN) perception and the underlying cortical structural network are altered by aging, and these aging-induced changes could be initiated during middle age. However, the mechanism behind the relationship between auditory performance and neural substrates of speech perception in middle-aged individuals remains unclear. In this study, we measured the structural volumes of selected neuroanatomical regions involved in speech and hearing processing to establish their association with speech perception ability in middle-aged adults.

METHODS

Sentence perception in quiet and noisy conditions was behaviorally measured in 2 different age groups: young (20-39 years old) and middle-aged (40-59-year-old) adults. Anatomical magnetic resonance images were taken to assess the gray matter volume of specific parcellated brain areas associated with speech perception. The relationships between these and behavioral auditory performance with age were determined.

RESULTS

The middle-aged adults showed poorer speech perception in both quiet and noisy conditions than the young adults. Neuroanatomical data revealed that the normalized gray matter volume in the left superior temporal gyrus, which is closely related to acoustic and phonological processing, is associated with behavioral SiN perception in the middle-aged group. In addition, the normalized gray matter volumes in multiple cortical areas seem to decrease with age.

CONCLUSION

The results indicate that SiN perception in middle-aged adults is closely related to the brain region responsible for lower-level speech processing, which involves the detection and phonemic representation of speech. Nonetheless, the higher-order cortex may also contribute to age-induced changes in auditory performance.

The Impact of Traumatic Brain Injury on Binaural Processing in Young and Middle-Age Adults

PURPOSE

This study examined the impact of traumatic brain injury (TBI) on self-perceived hearing and suprathreshold binaural processing in young and middle-age adults.

METHOD

Ninety-three adults with normal hearing (thresholds ≤ 25 dB HL, 250-4000 Hz) participated in one of four groups: 38 young adults, 23 young adults with TBI, 16 middle-age adults, and 16 middle-age adults with TBI. Self-perceived hearing difficulty was measured via questionnaires. Binaural processing was measured using dichotic word recognition, the Listening in Spatialized Noise-Sentences Test (LiSN-S), and the 500-Hz masking level difference (MLD). For each participant, a composite binaural processing (CBP) score was calculated to obtain a global metric of binaural processing performance. The CBP was composed of six measures from the three behavioral tests, including the S0N0 and SπN0 thresholds from the 500-Hz MLD, the low- and high-cue speech recognition thresholds from the LiSN-S, and the free and directed recall ear advantages from the dichotic word test.

RESULTS

The middle-age TBI group reported significantly greater degrees of self-perceived hearing difficulty than the other groups. On average, the middle-age TBI group performed poorer on the individual binaural processing tests; however, the differences were significant for the S0N0 and SπN0 MLD thresholds only. Results for the global metric of binaural processing revealed significantly poorer CBP scores for the middle-age TBI group compared to the other groups.

CONCLUSIONS

Results demonstrate that both age and a positive history of TBI contributed to deficits in suprathreshold binaural processing. Middle-age adults with a history of TBI are at risk for experiencing presenescent deficits in suprathreshold binaural processing deficits, despite having clinically normal hearing.

An Exploratory Study of Walking, Listening, and Remembering in Younger and Middle-Aged Adults

PURPOSE

The purpose of this study was to assess how needing to listen and remember information while walking affects speech perception, memory task performance, and gait in younger and middle-aged adults.

METHOD

Four gait parameters (stride duration, step variability, whole-body center of mass acceleration, and mediolateral head acceleration) were measured when younger and middle-aged participants stood or walked on a treadmill while they simultaneously completed a speech-on-speech perception task and a preload memory task, singly and in combination.

RESULTS

Speech perception was significantly poorer for middle-aged than for younger participants. Performance on the speech perception measure did not differ significantly between walking and standing for either group of participants, but the additional cognitive load of the memory task reduced performance on the speech perception task. Memory task performance was significantly poorer when combined with the speech perception task than when measured in isolation for both participant groups, but no further declines were noted when participants were also walking. Mediolateral head acceleration, which has been linked to loss of balance, was significantly greater during multitask trials, as compared to when participants were only walking without being required to listen or remember. Post hoc analysis showed that dual- and multitask influences on mediolateral head acceleration were more prominent for middle-aged than for younger participants. Stride duration was longer in the multitask condition than when participants were only walking.

CONCLUSIONS

Results of this exploratory study indicate that gait may be impacted when individuals (both younger and middle-aged) are listening and remembering while walking. Data also substantiate prior findings of early age-related declines in the perception of speech in the presence of understandable speech maskers.

Age-related reduction of amplitude modulation frequency selectivity

The perception of amplitude modulations (AMs) has been characterized by a frequency-selective process in the temporal envelope domain and simulated in computational auditory processing and perception models using a modulation filterbank. Such AM frequency-selective processing has been argued to be critical for the perception of complex sounds, including speech. This study aimed at investigating the effects of age on behavioral AM frequency selectivity in young (n = 11, 22-29 years) versus older (n = 10, 57-77 years) listeners with normal hearing, using a simultaneous AM masking paradigm with a sinusoidal carrier (2.8 kHz), target modulation frequencies of 4, 16, 64, and 128 Hz, and narrowband-noise modulation maskers. A reduction of AM frequency selectivity by a factor of up to 2 was found in the older listeners. While the observed AM selectivity co-varied with the unmasked AM detection sensitivity, the age-related broadening of the masked threshold patterns remained stable even when AM sensitivity was similar across groups for an extended stimulus duration. The results from the present study might provide a valuable basis for further investigations exploring the effects of age and reduced AM frequency selectivity on complex sound perception as well as the interaction of age and hearing impairment on AM processing and perception.

Age effects on cognitive functions and speech-in-noise processing: An event-related potential study with cochlear-implant users and normal-hearing listeners

A cochlear implant (CI) can partially restore hearing in individuals with profound sensorineural hearing loss. However, electrical hearing with a CI is limited and highly variable. The current study aimed to better understand the different factors contributing to this variability by examining how age affects cognitive functions and cortical speech processing in CI users. Electroencephalography (EEG) was applied while two groups of CI users (young and elderly; N = 13 each) and normal-hearing (NH) listeners (young and elderly; N = 13 each) performed an auditory sentence categorization task, including semantically correct and incorrect sentences presented either with or without background noise. Event-related potentials (ERPs) representing earlier, sensory-driven processes (N1-P2 complex to sentence onset) and later, cognitive-linguistic integration processes (N400 to semantically correct/incorrect sentence-final words) were compared between the different groups and speech conditions. The results revealed reduced amplitudes and prolonged latencies of auditory ERPs in CI users compared to NH listeners, both at earlier (N1, P2) and later processing stages (N400 effect). In addition to this hearing-group effect, CI users and NH listeners showed a comparable background-noise effect, as indicated by reduced hit rates and reduced (P2) and delayed (N1/P2) ERPs in conditions with background noise. Moreover, we observed an age effect in CI users and NH listeners, with young individuals showing improved specific cognitive functions (working memory capacity, cognitive flexibility and verbal learning/retrieval), reduced latencies (N1/P2), decreased N1 amplitudes and an increased N400 effect when compared to the elderly. In sum, our findings extend previous research by showing that the CI users' speech processing is impaired not only at earlier (sensory) but also at later (semantic integration) processing stages, both in conditions with and without background noise. Using objective ERP measures, our study provides further evidence of strong age effects on cortical speech processing, which can be observed in both the NH listeners and the CI users. We conclude that elderly individuals require more effortful processing at sensory stages of speech processing, which however seems to be at the cost of the limited resources available for the later semantic integration processes.

Auditory steady state responses elicited by silent gaps embedded within a broadband noise

Background

Auditory temporal processing plays an important role in speech comprehension. Usually, behavioral tests that require subjects to detect silent gaps embedded within a continuous sound are used to assess the ability of auditory temporal processing in humans. To evaluate auditory temporal processing objectively, the present study aimed to measure the auditory steady state responses (ASSRs) elicited by silent gaps of different lengths embedded within a broadband noise. We presented a broadband noise with 40-Hz silent gaps of 3.125, 6.25, and 12.5 ms.

Results

The 40-Hz silent gaps of 3.125, 6.25, and 12.5 ms elicited clear ASSRs. Longer silent gaps elicited larger ASSR amplitudes and ASSR phases significantly differed between conditions.

Conclusion

The 40 Hz gap-evoked ASSR contributes to our understanding of the neural mechanisms underlying auditory temporal processing and may lead to the development of objective measures of auditory temporal acuity in humans.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00712-0.

A Clinical Paradigm for Listening Effort Assessment in Middle-Aged Listeners

Listening effort (LE) has been known to characterize speech recognition in noise regardless of hearing sensitivity and age. Whereas the behavioral measure of dual-task paradigm effectively manifests the cognitive cost that listeners exert when processing speech in background noise, there is no consensus as to a clinical procedure that might best express LE. In order to assess the cognitive load underlying speech recognition in noise and promote counselling for coping strategies, a feasible clinical paradigm is warranted. The ecological validity of such a paradigm might best be demonstrated in middle-aged adults, exhibiting intact hearing sensitivity on one hand, however, experiencing difficulties in degraded listening conditions, unaware of the implicated cognitive cost of speech recognition in noise. To this end, we constructed a dual-task paradigm that consists of a primary task of sentences-in-noise recognition and a secondary task of simple visual colored-shape matching. Research objective was to develop a clinical paradigm for the assessment of LE in middle-aged adults. Participants were 17 middle-aged adults (mean age of 52.81 years) and 23 young adults (mean age of 24.90 years). All participants had normal hearing according to age. Speech stimuli consisted of the Hebrew Matrix sentences in noise test. SRTn was obtained for 80% correct identification. Visual stimuli were colored geometric shapes. Outcome measures were obtained initially for each task separately, to establish performance ability, and then obtained simultaneously. Reaction time and accuracy in the secondary task were the defined metrics for LE. Results: LE was indicated for both groups, however, was more pronounced in the middle-aged, manifested in the visual accuracy and reaction time metrics. Both groups maintained the 80% correct recognition-in-noise in the dual-task, however, the middle-aged group necessitated a better SNR of 1.4dB than the normal hearing group. Moreover, the middle-aged group was taxed in a greater prolongation of reaction time, in order to uphold the correct recognition. Conclusion: a dual-task paradigm consisting of sentences-in-noise primary task combined with a simple secondary task successfully showed different manifestations of LE in middle-aged adults compared to young adults, thus approximating the use of such a paradigm in a clinical setting.

Postural Control While Listening in Younger and Middle-Aged Adults

OBJECTIVES

The motivation for this research is to determine whether a listening-while-balancing task would be sensitive to quantifying listening effort in middle age. The premise behind this exploratory work is that a decrease in postural control would be demonstrated in challenging acoustic conditions, more so in middle-aged than in younger adults.

DESIGN

A dual-task paradigm was employed with speech understanding as one task and postural control as the other. For the speech perception task, participants listened to and repeated back sentences in the presence of other sentences or steady-state noise. Targets and maskers were presented in both spatially-coincident and spatially-separated conditions. The postural control task required participants to stand on a force platform either in normal stance (with feet approximately shoulder-width apart) or in tandem stance (with one foot behind the other). Participants also rated their subjective listening effort at the end of each block of trials.

RESULTS

Postural control was poorer for both groups of participants when the listening task was completed at a more adverse (vs. less adverse) signal-to-noise ratio. When participants were standing normally, postural control in dual-task conditions was negatively associated with degree of high-frequency hearing loss, with individuals who had higher pure-tone thresholds exhibiting poorer balance. Correlation analyses also indicated that reduced speech recognition ability was associated with poorer postural control in both single- and dual-task conditions. Middle-aged participants exhibited larger dual-task costs when the masker was speech, as compared to when it was noise. Individuals who reported expending greater effort on the listening task exhibited larger dual-task costs when in normal stance.

CONCLUSIONS

Listening under challenging acoustic conditions can have a negative impact on postural control, more so in middle-aged than in younger adults. One explanation for this finding is that the increased effort required to successfully listen in adverse environments leaves fewer resources for maintaining balance, particularly as people age. These results provide preliminary support for using this type of ecologically-valid dual-task paradigm to quantify the costs associated with understanding speech in adverse acoustic environments.

Papesh M, Gallun FJ. A Questionnaire Survey of Current Rehabilitation Practices for Adults With Normal Hearing Sensitivity Who Experience Auditory Difficulties

Purpose A questionnaire survey was conducted to collect information from clinical audiologists about rehabilitation options for adult patients who report significant auditory difficulties despite having normal or near-normal hearing sensitivity. This work aimed to provide more information about what audiologists are currently doing in the clinic to manage auditory difficulties in this patient population and their views on the efficacy of recommended rehabilitation methods. Method A questionnaire survey containing multiple-choice and open-ended questions was developed and disseminated online. Invitations to participate were delivered via e-mail listservs and through business cards provided at annual audiology conferences. All responses were anonymous at the time of data collection. Results Responses were collected from 209 participants. The majority of participants reported seeing at least one normal-hearing patient per month who reported significant communication difficulties. However, few respondents indicated that their location had specific protocols for the treatment of these patients. Counseling was reported as the most frequent rehabilitation method, but results revealed that audiologists across various work settings are also successfully starting to fit patients with mild-gain hearing aids. Responses indicated that patient compliance with computer-based auditory training methods was regarded as low, with patients generally preferring device-based rehabilitation options. Conclusions Results from this questionnaire survey strongly suggest that audiologists frequently see normal-hearing patients who report auditory difficulties, but that few clinicians are equipped with established protocols for diagnosis and management. While many feel that mild-gain hearing aids provide considerable benefit for these patients, very little research has been conducted to date to support the use of hearing aids or other rehabilitation options for this unique patient population. This study reveals the critical need for additional research to establish evidence-based practice guidelines that will empower clinicians to provide a high level of clinical care and effective rehabilitation strategies to these patients.

Consonant and vowel articulation accuracy in younger and middle-aged Spanish healthy adults

Children acquire vowels earlier than consonants, and the former are less vulnerable to speech disorders than the latter. This study explores the hypothesis that a similar contrast exists later in life and that consonants are more vulnerable to ageing than vowels. Data was obtained with two experiments comparing the speech of Younger Adults (YAs) and Middle–aged Adults (MAs). In the first experiment an Automatic Speech Recognition (ASR) system was trained with a balanced corpus of 29 YAs and 27 MAs. The productions of each speaker were obtained in a Spanish language word (W) and non–word (NW) repetition task. The performance of the system was evaluated with the same corpus used for training using a cross validation approach. The ASR system recognized to a similar extent the Ws of both groups of speakers, but it was more successful with the NWs of the YAs than with those of the MAs. Detailed error analysis revealed that the MA speakers scored below the YA speakers for consonants and also for the place and manner of articulation features; the results were almost identical in both groups of speakers for vowels and for the voicing feature. In the second experiment a group of healthy native listeners was asked to recognize isolated syllables presented with background noise. The target speakers were one YA and one MA that had taken part in the first experiment. The results were consistent with those of the ASR experiment: the manner and place of articulation were better recognized, and vowels and voicing were worse recognized, in the YA speaker than in the MA speaker. We conclude that consonant articulation is more vulnerable to ageing than vowel articulation. Future studies should explore whether or not these early and selective changes in articulation accuracy might be caused by changes in speech perception skills (e.g., in auditory temporal processing).

Encoding of a binaural speech stimulus at the brainstem level in middle-aged adults

OBJECTIVE

Binaural hearing is facilitated by neural interactions in the auditory pathway. Ageing results in impairment of localisation and listening in noisy situations without any significant hearing loss. The present study focused on comparing the binaural encoding of a speech stimulus at the subcortical level in middle-aged versus younger adults, based on speech-evoked auditory brainstem responses.

METHODS

Thirty participants (15 young adults and 15 middle-aged adults) with normal hearing sensitivity (less than 15 dB HL) participated in the study. The speech-evoked auditory brainstem response was recorded monaurally and binaurally with a 40-ms /da/ stimulus. Fast Fourier transform analysis was utilised.

RESULTS

An independent sample t-test revealed a significant difference between the two groups in fundamental frequency (F0) amplitude recorded with binaural stimulation.

CONCLUSION

The present study suggested that ageing results in degradation of F0 encoding, which is essential for the perception of speech in noise.

Cross-sectional study on hearing loss and auditory reaction time before and after spinal anesthesia with marcaine 0.5% in patients undergoing elective surgery

Background

Hearing loss is a rarely reported complication of spinal anesthesia. The purpose of this study is to assess the effects of 0.5% Maracine (bupivacaine) on hearing threshold and auditory reaction time before and after spinal anesthesia among patients undergoing elective surgery.

Materials and methods

This is a descriptive cross-sectional study performed on 60 patients undergoing elective surgery with ASA Class II and II anesthesia (0.5% bupivacaine) at Khorramabad Nursing Home. After obtaining consent from the patients, audiometry and tympanometry tests were performed using AZ80 and Madsen otoflex tympanometer and related findings including the presence or absence of hearing loss at various frequencies, before and after the surgery, were noted in a form for each patients along with their demographic data. SPSS 21 was used for statistical analysis and the data were analyzed using descriptive statistics and chi-square inferential tests.

Results

At low frequencies of 250 and 500 Hz, no significant difference in pre- and postoperative hearing threshold in the right ear (P > 0.05) was seen, but at frequencies above 500 Hz, the hearing threshold was significantly decreased after surgery, (P < 0.05). In the left ear at 250, 1000, 3000, and 8000 Hz, there was no significant difference (P > 0.05) between pre- and postoperative hearing threshold. The results of this study showed that the preoperative hearing threshold for men and women did not differ and the auditory threshold and auditory response time after surgery did not differ between the two sexes (P > 0.05). Similarly, the difference was not correlated with the age and the levels of anesthesia (P > 0.05). The results also showed that changes in mean arterial blood pressure (MAP) and heart rate above 30% of baseline were also not correlated with hearing loss (P > 0.05).

Conclusions

The results showed that at certain frequencies, hearing loss was observed in both ears after spinal anesthesia with 5% Marcaine, but this hearing loss was not related to age, sex, and spinal anesthesia level. The results also showed that changes in mean arterial blood pressure (MAP) and heart rate above 30% of baseline did not correlate with hearing loss.

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Hearing loss is a rarely reported complication of spinal anesthesia.

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Hearing loss in both ears is observed after spinal anesthesia with 5% Marcaine.

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Changes in MAP and heart rate greater than 30% of baseline is not associated with the hearing loss.

Hearing and speech processing in midlife

Middle-aged adults often report a decline in their ability to understand speech in adverse listening situations. However, there has been relatively little research devoted to identifying how early aging affects speech processing, as the majority of investigations into senescent changes in speech understanding compare performance in groups of young and older adults. This paper provides an overview of research on hearing and speech perception in middle-aged adults. Topics covered include both objective and subjective (self-perceived) hearing and speech understanding, listening effort, and audiovisual speech perception. This review ends with justification for future research needed to define the nature, consequences, and remediation of hearing problems in middle-aged adults.

The Impact of Speech Recognition Testing on State Anxiety in Young, Middle-Age, and Older Adults

Purpose This study assessed state anxiety as a function of speech recognition testing using three clinical measures of speech in noise and one clinical measure of dichotic speech recognition. Method Thirty young adults, 30 middle-age adults, and 25 older adults participated. State anxiety was measured pre- and post-speech recognition testing using the State-Trait Anxiety Inventory. Speech recognition was measured with the Revised Speech Perception in Noise Test, the Quick Speech-in-Noise Test, the Words-in-Noise Test, and the Dichotic Digits Test (DDT). Results Speech recognition performance was as expected: Older adults performed significantly poorer on all measures as compared to the young adults and significantly poorer on the Revised Speech Perception in Noise Test, the Quick Speech-in-Noise Test, and the Words-in-Noise Test as compared to the middle-age adults. On average, State-Trait Anxiety Inventory scores increased posttesting, with the middle-age adults exhibiting significantly greater increases in state anxiety as compared to the young and older adults. Increases in state anxiety were significantly greater for the DDT relative to the speech-in-noise tests for the middle-age adults only. Poorer DDT recognition performance was associated with higher levels of state anxiety. Conclusions Increases in state anxiety were observed after speech-in-noise and dichotic listening testing for all groups, with significant increases seen for the young and middle-age adults. Although the exact mechanisms could not be determined, multiple factors likely influenced the observed increases in state anxiety, including task difficulty, individual proficiency, and age.

Psychoacoustic and Demographic Factors for Speech Recognition of Older Adult Cochlear Implant Users

Purpose This study aimed to evaluate the effects of aging and cochlear implant (CI) on psychoacoustic and speech recognition abilities and to assess the relative contributions of psychoacoustic and demographic factors to speech recognition of older CI (OCI) users. Method Twelve OCI users, 12 older acoustic-hearing (OAH) listeners age-matched to OCI users, and 12 younger normal-hearing (YNH) listeners underwent tests of temporal amplitude modulation detection, temporal gap detection in noise, and spectral-temporal modulated ripple discrimination. Speech reception thresholds were measured for sentence recognition in multitalker, speech-babble noise. Results Statistical analyses showed that, for the small sample of OAH listeners, the degree of hearing loss did not significantly affect any outcome measure. Temporal resolution, spectral resolution, and speech recognition all significantly degraded with both age and the use of a CI (i.e., YNH better than OAH and OAH better than OCI performance). Although both were significantly correlated with OCI users' speech recognition, the duration of CI use no longer had a significant effect on speech recognition once the effect of spectral-temporal ripple discrimination performance was taken into account. For OAH listeners, the only significant predictor of speech recognition was temporal gap detection performance. Conclusion The preliminary results suggest that speech recognition of OCI users may improve with longer duration of CI use, mainly due to higher perceptual acuity to spectral-temporal modulated ripples in acoustic stimuli.

Evidence for enhanced neural tracking of the speech envelope underlying age-related speech-in-noise difficulties

When we grow older, understanding speech in noise becomes more challenging. Research has demonstrated the role of auditory temporal and cognitive deficits in these age-related speech-in-noise difficulties. To better understand the underlying neural mechanisms, we recruited young, middle-aged, and older normal-hearing adults and investigated the interplay between speech understanding, cognition, and neural tracking of the speech envelope using electroencephalography. The stimuli consisted of natural speech masked by speech-weighted noise or a competing talker and were presented at several subject-specific speech understanding levels. In addition to running speech, we recorded auditory steady-state responses at low modulation frequencies to assess the effect of age on nonspeech sounds. The results show that healthy aging resulted in a supralinear increase in the speech reception threshold, i.e., worse speech understanding, most pronounced for the competing talker. Similarly, advancing age was associated with a supralinear increase in envelope tracking, with a pronounced enhancement for older adults. Additionally, envelope tracking was found to increase with speech understanding, most apparent for older adults. Because we found that worse cognitive scores were associated with enhanced envelope tracking, our results support the hypothesis that enhanced envelope tracking in older adults is the result of a higher activation of brain regions for processing speech, compared with younger adults. From a cognitive perspective, this could reflect the inefficient use of cognitive resources, often observed in behavioral studies. Interestingly, the opposite effect of age was found for auditory steady-state responses, suggesting a complex interplay of different neural mechanisms with advancing age.NEW & NOTEWORTHY We measured neural tracking of the speech envelope across the adult lifespan and found a supralinear increase in envelope tracking with age. Using a more ecologically valid approach than auditory steady-state responses, we found that young and older, as well as middle-aged, normal-hearing adults showed an increase in envelope tracking with increasing speech understanding and that this association is stronger for older adults.

Lexical Influences on Errors in Masked Speech Perception in Younger, Middle-Aged, and Older Adults

Purpose In situations with a competing talker, lexical properties of words in both streams affect the recognition of words in the to-be-attended target stream. In this study, we tested whether these lexical properties also influence the type of errors made by listeners across the adult life span. Method Errors from a corpus collected by Helfer and Jesse (2015) were categorized as phonologically similar to words in the target and/or masker streams. Younger, middle-aged, and older listeners had produced these errors when trying to identify key words from a target stream while ignoring a single-talker masker. Neighborhood density and lexical frequency of target words and masker words had been manipulated independently. Results Lexical properties of target words influenced all types of errors. With higher frequency maskers, the probability of responding with a masker word increased and the phonological influence of target words decreased. Lower levels of lexical competition for maskers increased the probability that listeners reported a word phonologically related to both masker and target words. The influence of masker words increased across the adult life span, as evidenced by phonological intrusions into responses and the temporary failure in selectively attending to the target stream. The effects of lexical properties on error patterns, however, were consistent across age groups. Conclusions The ease of recognition of words in both attended and unattended speech influences the breakdown of speech perception. These influences remain robust across the adult life span.

The Influence of Hearing Aid Gain on Gap-Detection Thresholds for Children and Adults With Hearing Loss

OBJECTIVES

The objective of this experiment was to examine the contributions of audibility to the ability to perceive a gap in noise for children and adults. Sensorineural hearing loss (SNHL) in adulthood is associated with a deficit in gap detection. It is well known that reduced audibility in adult listeners with SNHL contributes to this deficit; however, it is unclear the extent to which hearing aid amplification can restore gap-detection thresholds, and the effect of childhood SNHL on gap-detection thresholds have not been described. For adults, it was hypothesized that restoring the dynamic range of hearing for listeners with SNHL would lead to approximately normal gap-detection thresholds. Children with normal hearing (NH) exhibit poorer gap-detection thresholds than adults. Because of their hearing loss, children with SNHL have less auditory experience than their peers with NH. Yet, it is unknown the extent to which auditory experience impacts their ability to perceive gaps in noise. Even with the provision of amplification, it was hypothesized that children with SNHL would show a deficit in gap detection, relative to their peers with normal hearing, because of reduced auditory experience.

DESIGN

The ability to detect a silent interval in noise was tested by adapting the stimulus level required for detection of gap durations between 3 and 20 ms for adults and children with and without SNHL. Stimulus-level thresholds were measured for participants with SNHL without amplification and with two prescriptive procedures-the adult and child versions of the desired sensation level i/o program-using a hearing aid simulator. The child version better restored the normal dynamic range than the adult version. Adults and children with NH were tested without amplification.

RESULTS

When fitted using the procedure that best restored the dynamic range, adults with SNHL had stimulus-level thresholds similar to those of adults with normal hearing. Compared to the children with NH, the children with SNHL required a higher stimulus level to detect a 5-ms gap, despite having used the procedure that better restored the normal dynamic range of hearing. Otherwise, the two groups of children had similar stimulus-level thresholds.

CONCLUSION

These findings suggest that apparent deficits in temporal resolution, as measured using stimulus-level thresholds for the detection of gaps, are dependent on age and audibility. These novel results indicate that childhood SNHL may impair temporal resolution as measured by stimulus-level thresholds for the detection of a gap in noise. This work has implications for understanding the effects of amplification on the ability to perceive temporal cues in speech.

The Effects of Static and Moving Spectral Ripple Sensitivity on Unaided and Aided Speech Perception in Noise

PURPOSE

This study evaluated whether certain spectral ripple conditions were more informative than others in predicting ecologically relevant unaided and aided speech outcomes.

METHOD

A quasi-experimental study design was used to evaluate 67 older adult hearing aid users with bilateral, symmetrical hearing loss. Speech perception in noise was tested under conditions of unaided and aided, auditory-only and auditory-visual, and 2 types of noise. Predictors included age, audiometric thresholds, audibility, hearing aid compression, and modulation depth detection thresholds for moving (4-Hz) or static (0-Hz) 2-cycle/octave spectral ripples applied to carriers of broadband noise or 2000-Hz low- or high-pass filtered noise.

RESULTS

A principal component analysis of the modulation detection data found that broadband and low-pass static and moving ripple detection thresholds loaded onto the first factor whereas high-pass static and moving ripple detection thresholds loaded onto a second factor. A linear mixed model revealed that audibility and the first factor (reflecting broadband and low-pass static and moving ripples) were significantly associated with speech perception performance. Similar results were found for unaided and aided speech scores. The interactions between speech conditions were not significant, suggesting that the relationship between ripples and speech perception was consistent regardless of visual cues or noise condition. High-pass ripple sensitivity was not correlated with speech understanding.

CONCLUSIONS

The results suggest that, for hearing aid users, poor speech understanding in noise and sensitivity to both static and slow-moving ripples may reflect deficits in the same underlying auditory processing mechanism. Significant factor loadings involving ripple stimuli with low-frequency content may suggest an impaired ability to use temporal fine structure information in the stimulus waveform. Support is provided for the use of spectral ripple testing to predict speech perception outcomes in clinical settings.

The effects of preceding sound and stimulus duration on measures of suppression in younger and older adults

Despite clinically normal audiometric thresholds, some older adults may experience difficulty in tasks such as understanding speech in a noisy environment. One potential reason may be reduced cochlear nonlinearity. A sensitive measure of cochlear nonlinearity is two-tone suppression, which is a reduction in the auditory system's response to one tone in the presence of a second tone. Previous research has been mixed on whether suppression decreases with age in humans. Studies of efferent cochlear gain reduction also suggest that stimulus duration should be considered in measuring suppression. In the present study, suppression was first measured psychoacoustically using stimuli that were too short to result in gain reduction. The potential effect of efferent cochlear gain reduction was then measured by using longer stimuli and presenting tonal or noise precursors before the shorter stimuli. Younger adults (ages 19-22 yr) and older adults (ages 57+ yr) with clinically normal hearing were tested. Suppression estimates decreased with longer stimuli or preceding sound which included the signal frequency, but did not decrease with preceding sound at the suppressor frequency. On average, the older group had lower suppression than the younger group, but this difference was not statistically significant.

Practice makes perfect: High performance gains in older adults engaged in selective attention within and across sensory modalities

Selective attention has been found to decline with aging, possibly depending on the sensory modality through which targets and distractors are presented. We investigated the capacity of older adults to improve performance on visual and auditory selective attention tasks. 31 younger (mean age = 22.8 years, SD = 2.1) and 29 older participants (mean age = 69.5 years, SD = 5.8) performed visual and auditory tasks with and without unimodal and cross-modal distraction across five practice sessions. Reaction time decreased with practice in both age groups. Strikingly, this performance improvement was similar across the age groups. Moreover, distractor modality did not affect performance gains in either age group. Older adults were disproportionally affected by cross-modal visual distraction, however, corroborating previous studies. This age-related effect was mitigated during the practice sessions. Finally, there was no transfer of practice to neuropsychological test performance. These results suggest a high capacity of older individuals to improve selective attention functions within and across sensory modalities.

Masking Differentially Affects Envelope-following Responses in Young and Aged Animals

Age-related hearing decline typically includes threshold shifts as well as reduced wave I auditory brainstem response (ABR) amplitudes due to cochlear synaptopathy/neuropathy, which may compromise precise coding of suprathreshold speech envelopes. This is supported by findings with older listeners, who have difficulties in envelope and speech processing, especially in noise. However, separating the effects of threshold elevation, synaptopathy, and degradation by noise on physiological representations may be difficult. In the present study, the effects of notched, low- and high-pass noise on envelope-following responses (EFRs) in aging were compared when sound levels (aged: 85-dB SPL; young: 60- to 80-dB SPL) were matched between groups peripherally, by matching wave I ABR amplitudes, or centrally by matching EFR amplitudes. Low-level notched noise reduced EFRs to sinusoidally amplitude-modulated (SAM) tones in young animals for notch widths up to 2 octaves. High-pass noise above the carrier frequency reduced EFRs. Young animals showed EFR reductions at lower noise levels. Low-pass noise did not reduce EFRs in either young or aged animals. High-pass noise may affect EFR amplitudes in young animals more than aged by reducing the contributions of high-frequency-sensitive inputs. EFRs to SAM tones in modulated noise (NAM) suggest that neurons of young animals can synchronize to NAM at lower sound levels and maintain dual AM representations better than older animals. The overall results show that EFR amplitudes are strongly influenced by aging and the presence of a competing sound that likely reduces or shifts the pool of responsive neurons.

The Effect of Aging and Priming on Same/Different Judgments Between Text and Partially Masked Speech

OBJECTIVES

It is well known from previous research that when listeners are told what they are about to hear before a degraded or partially masked auditory signal is presented, the speech signal "pops out" of the background and becomes considerably more intelligible. The goal of this research was to explore whether this priming effect is as strong in older adults as in younger adults.

DESIGN

Fifty-six adults-28 older and 28 younger-listened to "nonsense" sentences spoken by a female talker in the presence of a 2-talker speech masker (also female) or a fluctuating speech-like noise masker at 5 signal-to-noise ratios. Just before, or just after, the auditory signal was presented, a typed caption was displayed on a computer screen. The caption sentence was either identical to the auditory sentence or differed by one key word. The subjects' task was to decide whether the caption and auditory messages were the same or different. Discrimination performance was reported in d'. The strength of the pop-out perception was inferred from the improvement in performance that was expected from the caption-before order of presentation. A subset of 12 subjects from each group made confidence judgments as they gave their responses, and also completed several cognitive tests.

RESULTS

Data showed a clear order effect for both subject groups and both maskers, with better same-different discrimination performance for the caption-before condition than the caption-after condition. However, for the two-talker masker, the younger adults obtained a larger and more consistent benefit from the caption-before order than the older adults across signal-to-noise ratios. Especially at the poorer signal-to-noise ratios, older subjects showed little evidence that they experienced the pop-out effect that is presumed to make the discrimination task easier. On average, older subjects also appeared to approach the task differently, being more reluctant than younger subjects to report that the captions and auditory sentences were the same. Correlation analyses indicated a significant negative association between age and priming benefit in the two-talker masker and nonsignificant associations between priming benefit in this masker and either high-frequency hearing loss or performance on the cognitive tasks.

CONCLUSIONS

Previous studies have shown that older adults are at least as good, if not better, at exploiting context in speech recognition, as compared with younger adults. The current results are not in disagreement with those findings but suggest that, under some conditions, the automatic priming process that may contribute to benefits from context is not as strong in older as in younger adults.

Influence of temporal resolution skills in speech discrimination abilities of older subjects

Compromised temporal resolving power of the auditory system can be one of the main factors contributing to poor speech perception skills in the elderly. Very few of the earlier studies have systematically examined this aspect. Hence, the current study was designed with the following objectives: 1) To establish normative database of Gaps in Noise (GIN) test in elderly population in an Indian context. 2) To determine the relationship between speech discrimination skills and temporal resolution abilities in elderly individuals with normal hearing sensitivity. Thirty normal hearing elderly individuals (age range: 55-75 years; mean age: 59.86 ± 4.11 years) participated in the study. The audiological evaluation comprised of tympanometry, puretone and speech audiometry (Speech Reception Threshold-SRT, Speech Discrimination Score-SDS) and GIN. The results of the present study revealed mean Gap Detection Threshold (GDT) of 8.7 msec (SD = 3.38) in the right ear and 8.83 msec (SD = 2.86) in the left ear for the older participants. The mean Total Percentage Score (TPS) in the right ear was 47% (SD = 11.92) and 45% (SD = 11.29) in the left ear. These results suggest that temporal resolution abilities are poor in the elderly compared to the young and middle-aged group. There was no significant ear based difference on either GDT or TPS. The GDT was inversely correlated with speech discrimination performance. The TPS was positively correlated with SDS. This study clearly demonstrated a positive relationship between temporal resolution abilities and speech discrimination. The current database might be useful when assessing temporal resolution abilities in hearing impaired elderly individuals. Furthermore, all elderly individuals should undergo temporal resolution evaluation, irrespective of their hearing status, during audiological assessment.

Gap encoding by parvalbumin-expressing interneurons in auditory cortex

Synaptic inhibition shapes the temporal processing of sounds in auditory cortex, but the contribution of specific inhibitory cell types to temporal processing remains unclear. We recorded from parvalbumin-expressing (PV+) interneurons in auditory cortex to determine how they encode gaps in noise, a model of temporal processing more generally. We found that PV+ cells had stronger and more prevalent on-responses, off-responses, and postresponse suppression compared with presumed pyramidal cells. We summarize this pattern of differences as "deeper modulation" of gap responses in PV+ cells. Response latencies were also markedly faster for PV+ cells. We found a similar pattern of deeper modulation and faster latencies for responses to white noise bursts, suggesting that these are general properties of on- and off-responses in PV+ cells rather than specific features of gap encoding. These findings are consistent with a role for PV+ cells in providing dynamic gain control by pooling local activity. NEW & NOTEWORTHY We found that parvalbumin-expressing (PV+) interneurons in auditory cortex showed more deeply modulated responses to both gaps in noise and bursts of noise, suggesting that they are optimized for the rapid detection of stimulus transients.

Assessment of Disease-Specific and General Patient-Reported Outcome Measures of Hearing Health

Objective To assess disease-specific (Inner EAR) and general (Patient-Reported Outcomes Measurement Information System [PROMIS]) health status in patients reporting hearing loss and whether there is enough correlation between scales such that the general instrument alone could suffice. Study Design Correlation analysis of prospective cohort data. Setting Tertiary care academic medical center. Methods Adults presenting with a chief complaint of hearing loss completed the Inner EAR scale and the PROMIS instrument. Summary statistics, including means, percentiles, and measures of variance, were calculated. The Spearman ρ statistic was used to test the null hypothesis that there were no correlations between the Inner EAR composite or global score and PROMIS scores. Results The mean Inner EAR composite score was 35.6, while the global item had a mean score of 4.8. Mean PROMIS-10 scores were 16.0 for physical health and 15.3 for mental health. The global item and social item had mean scores of 3.6 and 3.8, respectively. Inner EAR composite scores were significantly correlated with the PROMIS mental health summary scores (Spearman ρ = 0.3, P = .0066) and the PROMIS social item score (Spearman ρ = 0.4, P = .0005). The Inner EAR global item was moderately correlated with the PROMIS social item score (Spearman ρ = 0.3, P = .0118), while there was no significant correlation between the Inner EAR global item and the PROMIS physical health, mental health, or global item scores. Conclusions Inner EAR and a subset of PROMIS scores have weak to moderate correlations. Disease-specific assessment still confers independent value.

Age-related changes in envelope-following responses at equalized peripheral or central activation

Previous work has debated about the comparisons of hearing abilities faced with alterations in hearing thresholds and evoked potentials between groups following acoustic trauma- or age-related changes. This study compares envelope-following responses (EFRs) of young and aged rats when sound levels were matched according to (1) wave I amplitudes of auditory brainstem responses (ABRs) elicited by 8-kHz tones or (2) EFR amplitudes evoked by sinusoidally amplitude-modulated (SAM) tones at 100% depth. Matched wave I amplitudes across age corresponded to approximately 20-dB sound level differences. For matched wave I, no age-related differences were observed in wave V amplitudes. However, EFRs recorded in silence were enhanced with aging at 100% but not at 25% depth, consistent with enhanced central gain in aging. For matched EFRs, there were no age-related differences in EFRs of amplitude modulation (AM) depth and AM frequency processing. These results suggest novel, objective measures beyond threshold to compensate for differences in auditory nerve activation and to differentiate peripheral and central contributions of EFRs.

Speech evoked auditory brainstem response and gap detection threshold in middle-aged individual

This study aimed at characterizing the gap detection threshold (GDT) and speech evoked ABR (SABR) in younger and middle-aged individuals. Two groups of subjects were participated in the study which includes 15 young adults in the age range of 15-25 years and 15 middle-aged individuals in the age range of 40-60 years. SABR with stimulus/da/of 40 ms and GDT were investigated on both groups. For SABR, Mann-Whitney U test revealed that ageing has significantly adverse effect on the encoding of F1 and F2 at brainstem level. However, no significant effect of ageing (till middle age) on the encoding of F0 was observed in present study. Mann-Whitney U test also showed significant longer latency of wave V in middle-aged individuals compared to younger adults. Furthermore, GDT was significantly better in younger adults compared to middle-aged individuals according to Mann-Whitney U test. This study also revealed no significant correlation between GDT and F0, F1, F2 for younger as well as middle-aged individuals. The findings of this study showed poor encoding of certain aspects of speech at brainstem level in middle-aged individuals compared to younger adults. This study also revealed deterioration of auditory processes in middle-aged individuals.

Aging and the effect of target-masker alignment

Similarity between target and competing speech messages plays a large role in how easy or difficult it is to understand messages of interest. Much research on informational masking has used highly aligned target and masking utterances that are very similar semantically and syntactically. However, listeners rarely encounter situations in real life where they must understand one sentence in the presence of another (or more than one) highly aligned, syntactically similar competing sentence(s). The purpose of the present study was to examine the effect of syntactic/semantic similarity of target and masking speech in different spatial conditions among younger, middle-aged, and older adults. The results of this experiment indicate that differences in speech recognition between older and younger participants were largest when the masker surrounded the target and was more similar to the target, especially at more adverse signal-to-noise ratios. Differences among listeners and the effect of similarity were much less robust, and all listeners were relatively resistant to masking, when maskers were located on one side of the target message. The present results suggest that previous studies using highly aligned stimuli may have overestimated age-related speech recognition problems.

Effect of conductive hearing loss on central auditory function

Introduction

It has been demonstrated that long-term Conductive Hearing Loss (CHL) may influence the precise detection of the temporal features of acoustic signals or Auditory Temporal Processing (ATP). It can be argued that ATP may be the underlying component of many central auditory processing capabilities such as speech comprehension or sound localization. Little is known about the consequences of CHL on temporal aspects of central auditory processing.

Objective

This study was designed to assess auditory temporal processing ability in individuals with chronic CHL.

Methods

During this analytical cross-sectional study, 52 patients with mild to moderate chronic CHL and 52 normal-hearing listeners (control), aged between 18 and 45 year-old, were recruited. In order to evaluate auditory temporal processing, the Gaps-in-Noise (GIN) test was used. The results obtained for each ear were analyzed based on the gap perception threshold and the percentage of correct responses.

Results

The average of GIN thresholds was significantly smaller for the control group than for the CHL group for both ears (right: p = 0.004; left: p < 0.001). Individuals with CHL had significantly lower correct responses than individuals with normal hearing for both sides (p < 0.001). No correlation was found between GIN performance and degree of hearing loss in either group (p > 0.05).

Conclusion

The results suggest reduced auditory temporal processing ability in adults with CHL compared to normal hearing subjects. Therefore, developing a clinical protocol to evaluate auditory temporal processing in this population is recommended.

The Impact of Minimal to Mild Sensorineural Hearing Loss in Adults

The relationship between the pure-tone audiogram and the categorization of normal hearing or a mild hearing loss fails to account for other important non-audiometric factors that impact hearing ability for approximately one-third of adults. In order to obtain a complete hearing profile of our patients who present with normal hearing or a mild hearing loss, it is necessary to consider more than simply the results of the pure-tone audiogram. Both subjective hearing handicap via questionnaire and suprathreshold auditory measures (especially in background noise) have been shown to be sensitive to deficits not captured by the pure-tone audiogram. Viable treatment options with demonstrated benefit, such as mild-gain amplification, should be considered for this population.

Efeitos da perda auditiva, escolaridade e idade no processamento temporal de idosos

RESUMO Objetivo: avaliar o efeito da perda auditiva, escolaridade e idade no processamento temporal de idosos. Métodos: foram avaliados 30 idosos, 15 com perda auditiva e baixa escolaridade e (Grupo 1) e 15 com audição normal e maior escolaridade (Grupo 2). Os participantes foram submetidos a avaliação audiológica, triagem cognitiva e avaliação do processamento temporal (resolução e ordenação temporal). Resultados: nota-se que os além da escolaridade os grupos se diferem em relação a idade, os idosos do Grupo 1 são mais velhos (p=0,024) e menos escolarizados (p=0.002). Os idosos do Grupo 1 apresentaram maior limiar e menor porcentagem de reconhecimento de gaps no ruido quando comparados ao desempenho dos idosos do Grupo 2 (GIN Limiar p=0,002; GIN % p=0,005). Os participantes de ambos os grupos apresentaram desempenhos similares na habilidade de ordenação temporal (p=0,691). Nesta amostra houve correlação negativa entre escolaridade e limiar de acuidade temporal (p=0,045), ou seja, quanto maior a escolaridade (em anos) menor o limiar de reconhecimento de gaps. Apesar dos grupos serem distintos em relação a faixa etaria, a idade dos idosos não afetou o desempenho para os testes comportamentais do processamento temporal. Conclusão: Idosos com perda de audição e menor escolaridade apresentam maior prejuizo na habilidade de resolução temporal. Não houve correlação da idade com desempenho nos testes temporais.

Speech Recognition in Noise by Younger and Older Adults

Objectives:

Purpose of the present study is to evaluate the effects of aging on temporal resolution and speech understanding in noise.

Methods:

Twenty-seven young and 33 older normal hearing adults participated in this study. Temporal resolution was investigated using the Gaps in Noise (GIN) test. Understanding sentences in noise was investigated using a Dutch sentences (LIST) test.

Results:

Results demonstrated that older adults have significantly worse temporal resolution scores and significantly greater difficulty understanding sentences in noise than younger adults. In the group of older adults, the ability to understand sentences in noise correlated with hearing and age. A stepwise regression analysis showed that age was the best predictor for the speech in noise results. However, temporal resolution correlated with hearing, not with age. Results from the GIN test did not correlate with the results from the LIST test.

Conclusions:

The present study shows that with advancing age, both temporal resolution and speech understanding in noise significantly diminish. Temporal resolution correlates with hearing, not age, while speech understanding correlates more with age than hearing. These results could have implications for the outcome of auditory prostheses in older adults, as both diminished temporal resolution and speech understanding have to be taken into account.

The Effect of Age on Listening Effort

PURPOSE

The objective of this study was to investigate the effect of age on listening effort.

METHOD

A dual-task paradigm was used to evaluate listening effort in different conditions of background noise. Sixty adults ranging in age from 20 to 77 years were included. A primary speech-recognition task and a secondary memory task were performed both separately and simultaneously. Multiple regression analyses were used to evaluate how age and hearing thresholds affect speech recognition and listening effort scores.

RESULTS

Results of the multiple regression analyses showed that age is a significant determinant of listening effort, whereby listening effort increases with increasing age even when age-related variance in speech recognition is partialled out. On the basis of the regression equations and the median score for listening effort, it was found that listening effort started to increase in the fourth decade of life.

CONCLUSIONS

This study was a first exploration of listening effort from young to older adults and showed that, independent of hearing sensitivity, listening effort increases with age. To be more specific, there is a need to further investigate the cognitive functions important for speech communication while exploring their possible relationship with listening effort.

Relatively effortless listening promotes understanding and recall of medical instructions in older adults

Communication success under adverse conditions requires efficient and effective recruitment of both bottom-up (sensori-perceptual) and top-down (cognitive-linguistic) resources to decode the intended auditory-verbal message. Employing these limited capacity resources has been shown to vary across the lifespan, with evidence indicating that younger adults out-perform older adults for both comprehension and memory of the message. This study examined how sources of interference arising from the speaker (message spoken with conversational vs. clear speech technique), the listener (hearing-listening and cognitive-linguistic factors), and the environment (in competing speech babble noise vs. quiet) interact and influence learning and memory performance using more ecologically valid methods than has been done previously. The results suggest that when older adults listened to complex medical prescription instructions with “clear speech,” (presented at audible levels through insertion earphones) their learning efficiency, immediate, and delayed memory performance improved relative to their performance when they listened with a normal conversational speech rate (presented at audible levels in sound field). This better learning and memory performance for clear speech listening was maintained even in the presence of speech babble noise. The finding that there was the largest learning-practice effect on 2nd trial performance in the conversational speech when the clear speech listening condition was first is suggestive of greater experience-dependent perceptual learning or adaptation to the speaker's speech and voice pattern in clear speech. This suggests that experience-dependent perceptual learning plays a role in facilitating the language processing and comprehension of a message and subsequent memory encoding.

Critérios de normalidade dos testes de resolução temporal: random gap detection test e gaps-in-noise

OBJETIVO: avaliar a resolução temporal em indivíduos audiologicamente normais entre 20 e 60 anos. MÉTODOS: 40 indivíduos de ambos os sexos, de 20 aos 60 anos de idade, divididos em quatro grupos etários contendo 10 indivíduos em cada grupo: Grupo I de 20 a 30 anos; Grupo II de 31 a 40 anos; Grupo III de 41 a 50 anos e Grupo IV de 51 a 60. Todos foram submetidos a procedimentos que fazem parte da rotina audiológica para caracterizar a audição periférica, e central com destaque nos testes de resolução temporal com tons puros, o Randon-gap-detection-test, e com ruído o Gaps-in-noise. RESULTADOS: os valores médios obtidos para o limiar de detecção de gap no teste Gaps-in-noise encontram-se em torno de seis milissegundos para os grupos 1 e 2 e de oito, nos grupos 3 e 4. Verificou-se limiar de detecção de gap obtido no teste Random-gap-detection-test com valor médio de 10 milissegundos para os grupos 1 e 2 e entre 10 e 15ms nos grupos 3 e 4. CONCLUSÃO: a habilidade de resolução temporal piora com o aumento da idade. Os valores de normalidade dos testes com segmentos de ruído (teste GIN - Gaps In Noise) e tom puro (teste RGDT - Random Gap Test Detection) são crescentes de acordo com a faixa etária avaliada.

Temporal Processing Deficits in Middle Age

PURPOSE

The purpose of this brief report is to provide a synopsis of recent work, primarily from the authors' laboratory, that points to the emergence of temporal processing deficits relatively early in the aging process.

METHOD

The approach taken was to provide a descriptive summary of selected published and current experiments focusing on the processing of temporal envelopes and fine structure.

CONCLUSION

Deficits in both temporal envelope and temporal fine structure processing are evident during middle age even while audiometric hearing sensitivity remains normal.

Competing Speech Perception in Middle Age

PURPOSE

This research forum article summarizes research from our laboratory that assessed middle-aged adults' ability to understand speech in the presence of competing talkers.

METHOD

The performance of middle-aged adults on laboratory-based speech understanding tasks was compared to that of younger and older adults.

RESULTS

Decline in the ability to understand speech in complex listening environments can be demonstrated in midlife. The specific auditory and cognitive contributors to these problems have yet to be established.

CONCLUSION

There is evidence that the ability to understand a target speech message in the presence of competing speech messages changes relatively early in the aging process. The nature and impact of these changes warrant further investigation.

Perceptual gap detection is mediated by gap termination responses in auditory cortex

BACKGROUND

Understanding speech in the presence of background noise often becomes increasingly difficult with age. These age-related speech processing deficits reflect impairments in temporal acuity. Gap detection is a model for temporal acuity in speech processing in which a gap inserted in white noise acts as a cue that attenuates subsequent startle responses. Lesion studies have shown that auditory cortex is necessary for the detection of brief gaps, and auditory cortical neurons respond to the end of the gap with a characteristic burst of spikes called the gap termination response (GTR). However, it remains unknown whether and how the GTR plays a causal role in gap detection. We tested this by optogenetically suppressing the activity of somatostatin- or parvalbumin-expressing inhibitory interneurons, or CaMKII-expressing excitatory neurons, in auditory cortex of behaving mice during specific epochs of a gap detection protocol.

RESULTS

Suppressing interneuron activity during the postgap interval enhanced gap detection. Suppressing excitatory cells during this interval attenuated gap detection. Suppressing activity preceding the gap had the opposite behavioral effects, whereas prolonged suppression across both intervals had no effect on gap detection.

CONCLUSIONS

In addition to confirming cortical involvement, we demonstrate here for the first time a causal relationship between postgap neural activity and perceptual gap detection. Furthermore, our results suggest that gap detection involves an ongoing comparison of pre- and postgap spiking activity. Finally, we propose a simple yet biologically plausible neural circuit that reproduces each of these neural and behavioral results.

Age-related decline in emotional prosody discrimination: acoustic correlates

It is now accepted that older adults have difficulty recognizing prosodic emotion cues, but it is not clear at what processing stage this ability breaks down. We manipulated the acoustic characteristics of tones in pitch, amplitude, and duration discrimination tasks to assess whether impaired basic auditory perception coexisted with our previously demonstrated age-related prosodic emotion perception impairment. It was found that pitch perception was particularly impaired in older adults, and that it displayed the strongest correlation with prosodic emotion discrimination. We conclude that an important cause of age-related impairment in prosodic emotion comprehension exists at the fundamental sensory level of processing.

Effect of Repetition Rate on Speech Evoked Auditory Brainstem Response in Younger and Middle Aged Individuals

Speech evoked auditory brainstem responses depicts the neural encoding of speech at the level of brainstem. This study was designed to evaluate the neural encoding of speech at the brainstem in younger population and middle-aged population at three different repetition rates (6.9, 10.9 and 15.4). Speech evoked auditory brainstem response was recorded from 84 participants (young participants=42, middle aged participants=42) with normal hearing sensitivity. The latency of wave V and amplitude of the fundamental frequency, first formant frequency and second formant frequency was calculated. Results showed that the latency of wave V was prolonged for middle-aged individuals for all three-repetition rates compared to the younger participants. The results of the present study also revealed that there was no difference in encoding of fundamental frequency between middle aged and younger individuals at any of the repetition rates. However, increase in repetition rate did affect the encoding of the fundamental frequency in middle-aged individuals. The above results suggest a differential effect of repetition rate on wave V latency and encoding of fundamental frequency. Further, it was noticed that repetition rate did not affect the amplitude of first formant frequency or second formant frequency in middle aged participants compared to the younger participants.

Stimulus and listener factors affecting age-related changes in competing speech perception

The purpose of this study was to examine associations among hearing thresholds, cognitive ability, and speech understanding in adverse listening conditions within and between groups of younger, middle-aged, and older adults. Participants repeated back sentences played in the presence of several types of maskers (syntactically similar and syntactically different competing speech from one or two other talkers, and steady-state speech-shaped noise). They also completed tests of auditory short-term/working memory, processing speed, and inhibitory ability. Results showed that group differences in accuracy of word identification and in error patterns differed depending upon the number of masking voices; specifically, older and middle-aged individuals had particular difficulty, relative to younger subjects, in the presence of a single competing message. However, the effect of syntactic similarity was consistent across subject groups. Hearing loss, short-term memory, processing speed, and inhibitory ability were each related to some aspects of performance by the middle-aged and older participants. Notably, substantial age-related changes in speech recognition were apparent within the group of middle-aged listeners.

A factor analysis of the SSQ (Speech, Spatial, and Qualities of Hearing Scale)

OBJECTIVE

The speech, spatial, and qualities of hearing questionnaire (SSQ) is a self-report test of auditory disability. The 49 items ask how well a listener would do in many complex listening situations illustrative of real life. The scores on the items are often combined into the three main sections or into 10 pragmatic subscales. We report here a factor analysis of the SSQ that we conducted to further investigate its statistical properties and to determine its structure.

DESIGN

Statistical factor analysis of questionnaire data, using parallel analysis to determine the number of factors to retain, oblique rotation of factors, and a bootstrap method to estimate the confidence intervals.

STUDY SAMPLE

1220 people who have attended MRC IHR over the last decade.

RESULTS

We found three clear factors, essentially corresponding to the three main sections of the SSQ. They are termed "speech understanding", "spatial perception", and "clarity, separation, and identification". Thirty-five of the SSQ questions were included in the three factors. There was partial evidence for a fourth factor, "effort and concentration", representing two more questions.

CONCLUSIONS

These results aid in the interpretation and application of the SSQ and indicate potential methods for generating average scores.