Auditory and cognitive abilities of children suspected of auditory processing disorder (APD)

Relationship Between Socioeconomic Status and Basic Auditory Processing in Young Adults

PURPOSE

The current study aimed at investigating the relationship between socioeconomic status (SES) and basic auditory processing in young adults with normal hearing. Specifically, we sought to determine whether SES metrics, including parental education, parental occupation, and individual education attainment, influenced performance on tasks of basic auditory processing. Secondarily, we also aimed at understanding the interactive effects of SES and working memory on basic auditory processing.

METHOD

A total of 38 young adults were included in the study. Self-reported SES measures were recorded through Likert scales, and auditory processing measures included tests for temporal fine structure (TFS) and spectrotemporal sensitivity (STS). Pearson correlation analyses were conducted to probe the relationships between SES indicators and auditory processing performance. Multiple linear regressions were conducted to understand the interactive effects of SES and working memory on auditory processing performance.

RESULTS

The analysis revealed no significant correlation between SES measures and basic auditory processing performance across TFS and STS tasks. Furthermore, analysis investigating the interaction between SES and working memory also yielded nonsignificant results. These findings indicate that, within this specific age cohort, SES information may not be indispensable for assessing basic auditory processing.

CONCLUSIONS

Our study suggests that SES may not significantly influence basic auditory processing in young adults with normal hearing. However, further research with larger sample sizes and longitudinal designs is warranted to confirm these findings and explore potential age-related differences in the impact of SES on auditory processing across the lifespan.

Relationship Between Cognitive Abilities and Basic Auditory Processing in Young Adults

PURPOSE

The diagnosis of auditory processing disorder (APD) is controversial particularly due to the influence of higher order factors of language and cognition on the diagnostic APD testing. As a result, there might be a need for testing for other domains (e.g., cognition) along with conducting the diagnostic APD testing to rule out the influence of other domains. In order to make recommendations on whether cognitive testing is needed along with the auditory processing testing, as a starting point, the current study was conducted to examine the relationship between cognitive abilities and basic auditory processing in young adults.

METHOD

A total of 38 young adults with normal audiometric thresholds between 250 and 8000 Hz participated in this study. They were tested on their executive function, language, processing speed, working memory, and episodic memory components of cognitive testing and tests for temporal fine structure and spectrotemporal sensitivity for auditory processing testing.

RESULTS

No significant correlation was found between the cognitive tests and the tests for basic auditory processing in young adults.

CONCLUSIONS

These findings present contrast to the existing findings in children and older adults where a stronger correlation between cognitive abilities and auditory processing has been found. The current findings suggest that testing for cognitive abilities may not be needed when testing for basic auditory processing in young adults.

Returning Individual Research Results to Vulnerable Individuals

Although issues associated with returning individual research results to study participants have been well explored, these issues have been less thoroughly investigated in vulnerable individuals and populations. Considerations regarding return of research results to these individuals and populations, including how best to ensure truly informed consent, how to minimize the risks and benefits of the return of research results, and how best to ensure justice may differ from those of the population at large. This article discusses the issues and challenges associated with the return of individual research results (such as genomic, proteomic, or other biomarker data) to potentially vulnerable individuals and populations, including those who may be vulnerable for cognitive, communicative, institutional, social, deferential, medical, economic, or social reasons. It explores factors that should be considered in the design, conduct, and oversight of ethically responsible research involving the return of research results to vulnerable individuals and populations and discuss recommendations for those engaged in this work.

Speech Perception in Noise Predicts Oral Narrative Comprehension in Children With Developmental Language Disorder

We examined the relative contribution of auditory processing abilities (tone perception and speech perception in noise) after controlling for short-term memory capacity and vocabulary, to narrative language comprehension in children with developmental language disorder. Two hundred and sixteen children with developmental language disorder, ages 6 to 9 years (Mean = 7; 6), were administered multiple measures. The dependent variable was children's score on the narrative comprehension scale of the Test of Narrative Language. Predictors were auditory processing abilities, phonological short-term memory capacity, and language (vocabulary) factors, with age, speech perception in quiet, and non-verbal IQ as covariates. Results showed that narrative comprehension was positively correlated with the majority of the predictors. Regression analysis suggested that speech perception in noise contributed uniquely to narrative comprehension in children with developmental language disorder, over and above all other predictors; however, tone perception tasks failed to explain unique variance. The relative importance of speech perception in noise over tone-perception measures for language comprehension reinforces the need for the assessment and management of listening in noise deficits and makes a compelling case for the functional implications of complex listening situations for children with developmental language disorder.

Effect of speech in noise training in the auditory and cognitive skills in children with auditory processing disorders

OBJECTIVES

Speech perception in the presence of background noise is identified as one of the most affected auditory processes in children with auditory processing disorders (APD). Mechanism of speech-in-noise perception is extensively studied and is reported to involve different auditory and cognitive skills. However previous research has reported mixed results investigating the relationship between the cognitive skills and speech-in-noise perception in children with APD. The present study intended to study the correlation between the speech-in-noise perception and other auditory and cognitive skills, and also to find the efficacy of speech-in-noise training in other auditory and cognitive skills in children with APD.

METHOD

The study imparted words in noise training utilizing monosyllable and trisyllable words in the presence of speech shaped noise and 4-talker babble. Participants included 20 children with APD, 10 of them in the experimental group who underwent the training and the remaining 10 served as controls. Auditory outcome measures included five behavioural APD tests and four digit span tests to assess cognition.

RESULTS

There was a significant improvement in the speech-in-noise perception measures, temporal processing measures (gap detection test and duration pattern test) and the backward, ascending and descending digit span measures after the training in participants in the experimental group. However, Spearman rank order correlation did not reveal a significant correlation between the speech-in-noise perception scores and any of the auditory or cognitive measures.

CONCLUSION

Even though there was no correlation within and between auditory and cognitive measures, speech-in-noise training improved the temporal processing skills as well as the working memory skills in children with APD supporting the relationship between the said processes. These relationships with evidence from further research could be utilized to design more effective treatment strategies for children with APD.

Auditory Processing Disorder and Its Comorbidities: A Need for Consistency in Test Cutoff Scores

Purpose No gold standard criteria exist for diagnosing developmental auditory processing disorder (APD). This study aimed to identify APD criteria, which are consistent with that used for comorbidities, and how comorbidities predicted APD. Method A retrospective study of 167 participants (males = 105, females = 62; age: 6-16 years; nonverbal IQ > 80) with suspected APD is presented. Five SCAN-3 tests evaluated auditory processing (AP). Comorbidities included attention-deficit/hyperactivity disorder, language impairment, and impaired manual dexterity, which were identified using percentile ≤ 5 in the Swanson, Nolan and Pelham parental rating scale; Children's Communication Checklist-2; and Movement Assessment Battery for Children-2, respectively. Results Percentiles ≤ 9, ≤ 5, and < 2 in two or more AP tests had sensitivities (specificities) of 76% (70.6%), 59.3% (76.5%), and 26% (82.4%), respectively, in predicting comorbidities, which were present in 150 of the 167 participants. The criterion of "≤ 9 percentile in two or more AP tests" (Approach I) diagnosed APD in 119 participants, and criterion "≤ 5 percentile in two or more AP tests or ≤ 5 percentile in one AP plus one or more measures of comorbidities" (Approach II) diagnosed 123. The combination of approaches diagnosed 128 participants (76.6%) with APD, of which 114 were diagnosed by each approach (89%). Language impairment and impaired manual dexterity, but not attention-deficit/hyperactivity disorder, predicted APD. Conclusions "Percentile ≤ 9 in two or more AP tests" or "percentile ≤ 5 in one AP plus one or more measures of comorbidities" are evidence-based APD diagnostic criteria. Holistic and interprofessional practice evaluating comorbidities including motor skills is important for APD.

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607.

Comparison of Questionnaire-Based and Performance-Based Screening Tools as Predictors of Auditory Processing Disorder

Purpose The purpose of this study was to compare questionnaire-based and performance-based screening tools as predictors of an auditory processing disorder (APD) diagnosis. The questionnaire-based screening tools used were the Children's Auditory Performance Scale, Fisher's Auditory Problems Checklist, and Buffalo Model Questionnaire-Revised. The performance-based screening tools were from the SCAN-3 screening tests, that is, Auditory Figure Ground, Competing Words Free Recall (CW-FR), and Gap Detection Test. Predictability was ascertained by comparing the scores from screening tools with those from diagnostic APD tests and with the final diagnosis of APD. Research Design This study is a retrospective single-observation study. Method The screening and diagnostic test results were retrospectively analyzed from the medical records of 85 individuals (female = 39) aged 7-23 years who were seen for APD assessment at Bloomsburg University's Clinic for Hearing and Balance. Each participant was assessed with at least two questionnaire-based and at least two performance-based screening tools. Results Spearman correlation coefficient analysis showed a moderate relationship within questionnaire-based screening tools, whereas there was no relationship between questionnaire- and performance-based tools. Notably, the performance-based CW-FR screening tool showed a significant relationship with five diagnostic tests. The questionnaire-based screening tools did not predict APD diagnosis. The performance-based tool CW-FR (φ = 0.33) and the SCAN-3 screening battery (φ = 0.44) predicted the diagnosis of APD. Conclusion A performance-based screening tool or battery can be used to determine whether additional diagnostic APD evaluation is warranted. Referral for diagnostic assessment should not be based solely on questionnaire-based screening tools.

Clinical Expertise Is Core to an Evidence-Based Approach to Auditory Processing Disorder: A Reply to Neijenhuis et al. 2019

The opinion article "An Evidence-based Perspective on Misconceptions Regarding Pediatric Auditory Processing Disorder" by Neijenhuis et al. (1) presents a distorted view of the evidence-based approach used in medicine. The authors focus on the amorphous non-diagnostic entity "listening difficulties" not auditory processing disorder (APD) and create confusion that could jeopardize clinical services to individuals with APD. In our perspective article, we rebut Neijenhuis et al. (1), and more importantly, we present a rationale for evidence-based practice founded on the premise that research on APD is only clinically applicable when conducted on clinical populations diagnosed with APD.

Auditory processing disorder evaluations and cognitive profiles of children with specific learning disorder

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Children with altered auditory processing exhibit a specific cognitive profile.

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Lower verbal and spatial reasoning performance are associated with altered auditory processing.

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Children with specific learning disorder should undergo a complete multimodal examination.

Objective

This study investigated the auditory sensory-perceptual level of specific learning disorder (SLD) and explored relationships among neuropsychological assessments for SLD, auditory processing, and short and long latencies of auditory event-related potentials (ERPs).

Methods

Fifteen children (7–14 years old) comprised the control group; 34 children comprised the SLD group. Audiologic assessments included tone audiometry, acoustic immittance measurements, acoustic reflex, central auditory processing, brainstem evoked response audiometry, and long latency potentials (P3 and N2). Children’s intelligence levels were assessed with 2 intelligence batteries, 1 verbal and 1 non-verbal, as well as with visuomotor skills.

Results

Multiple regression showed a significant interaction effect of APE tests and P3/N2 over Wechsler Scale performance in freedom of distractibility indexes and multiple subtests. Errors in the Bender Visual Motor Gestalt Test were predicted by lower parental education, lower performance in APE tests: dichotic digits and pediatric/synthetic sentence identification-ipsilateral, and longer P3/N2 latencies, particularly regarding integration and rotation distortions.

Conclusions

Children with altered auditory processing exhibit a specific cognitive profile, including lower verbal and spatial reasoning performance, that is sensitive to parental education level.

Significance

Children with SLD should undergo a complete multimodal examination to identify their specific difficulties and needs.

Working Memory and Auditory Processing in School-Age Children

Purpose

Our goal is to present the relationships between working memory (WM) and auditory processing abilities in school-age children.

Review and Discussion

We begin with an overview of auditory processing, the conceptualization of auditory processing disorder, and the assessment of auditory processing abilities in children. Next, we describe a model of WM and a model of auditory processing followed by their comparison. Evidence for the relationships between WM and auditory processing abilities in school-age children follows. Specifically, we present evidence for the association (or lack thereof) between WM/attention and auditory processing test performance.

Clinical Implications

In conclusion, we describe a new framework for understanding auditory processing abilities in children based on integrated evidence from cognitive science, hearing science, and language science. We also discuss clinical implications in children that could inform future research.

Children's Speech Perception in Noise: Evidence for Dissociation From Language and Working Memory

PURPOSE

We examined the association between speech perception in noise (SPIN), language abilities, and working memory (WM) capacity in school-age children. Existing studies supporting the Ease of Language Understanding (ELU) model suggest that WM capacity plays a significant role in adverse listening situations.

METHOD

Eighty-three children between the ages of 7 to 11 years participated. The sample represented a continuum of individual differences in attention, memory, and language abilities. All children had normal-range hearing and normal-range nonverbal IQ. Children completed the Bamford-Kowal-Bench Speech-in-Noise Test (BKB-SIN; Etymotic Research, 2005), a selective auditory attention task, and multiple measures of language and WM.

RESULTS

Partial correlations (controlling for age) showed significant positive associations among attention, memory, and language measures. However, BKB-SIN did not correlate significantly with any of the other measures. Principal component analysis revealed a distinct WM factor and a distinct language factor. BKB-SIN loaded robustly as a distinct 3rd factor with minimal secondary loading from sentence recall and short-term memory. Nonverbal IQ loaded as a 4th factor.

CONCLUSIONS

Results did not support an association between SPIN and WM capacity in children. However, in this study, a single SPIN measure was used. Future studies using multiple SPIN measures are warranted. Evidence from the current study supports the use of BKB-SIN as clinical measure of speech perception ability because it was not influenced by variation in children's language and memory abilities. More large-scale studies in school-age children are needed to replicate the proposed role played by WM in adverse listening situations.

On the Etiology of Listening Difficulties in Noise Despite Clinically Normal Audiograms

Many people with difficulties following conversations in noisy settings have “clinically normal” audiograms, that is, tone thresholds better than 20 dB HL from 0.1 to 8 kHz. This review summarizes the possible causes of such difficulties, and examines established as well as promising new psychoacoustic and electrophysiologic approaches to differentiate between them. Deficits at the level of the auditory periphery are possible even if thresholds remain around 0 dB HL, and become probable when they reach 10 to 20 dB HL. Extending the audiogram beyond 8 kHz can identify early signs of noise-induced trauma to the vulnerable basal turn of the cochlea, and might point to “hidden” losses at lower frequencies that could compromise speech reception in noise. Listening difficulties can also be a consequence of impaired central auditory processing, resulting from lesions affecting the auditory brainstem or cortex, or from abnormal patterns of sound input during developmental sensitive periods and even in adulthood. Such auditory processing disorders should be distinguished from (cognitive) linguistic deficits, and from problems with attention or working memory that may not be specific to the auditory modality. Improved diagnosis of the causes of listening difficulties in noise should lead to better treatment outcomes, by optimizing auditory training procedures to the specific deficits of individual patients, for example.

The Relationship between Types of Attention and Auditory Processing Skills: Reconsidering Auditory Processing Disorder Diagnosis

Measures of attention have been found to correlate with specific auditory processing tests in samples of children suspected of Auditory Processing Disorder (APD), but these relationships have not been adequately investigated. Despite evidence linking auditory attention and deficits/symptoms of APD, measures of attention are not routinely used in APD diagnostic protocols. The aim of the study was to examine the relationship between auditory and visual attention tests and auditory processing tests in children with APD and to assess whether a proposed diagnostic protocol for APD, including measures of attention, could provide useful information for APD management. A pilot study including 27 children, aged 7-11 years, referred for APD assessment was conducted. The validated test of everyday attention for children, with visual and auditory attention tasks, the listening in spatialized noise sentences test, the children's communication checklist questionnaire and tests from a standard APD diagnostic test battery were administered. Pearson's partial correlation analysis examining the relationship between these tests and Cochrane's Q test analysis comparing proportions of diagnosis under each proposed battery were conducted. Divided auditory and divided auditory-visual attention strongly correlated with the dichotic digits test, r = 0.68, p < 0.05, and r = 0.76, p = 0.01, respectively, in a sample of 20 children with APD diagnosis. The standard APD battery identified a larger proportion of participants as having APD, than an attention battery identified as having Attention Deficits (ADs). The proposed APD battery excluding AD cases did not have a significantly different diagnosis proportion than the standard APD battery. Finally, the newly proposed diagnostic battery, identifying an inattentive subtype of APD, identified five children who would have otherwise been considered not having ADs. The findings show that a subgroup of children with APD demonstrates underlying sustained and divided attention deficits. Attention deficits in children with APD appear to be centred around the auditory modality but further examination of types of attention in both modalities is required. Revising diagnostic criteria to incorporate attention tests and the inattentive type of APD in the test battery, provides additional useful data to clinicians to ensure careful interpretation of APD assessments.

Common Misconceptions Regarding Pediatric Auditory Processing Disorder

Pediatric hearing evaluation based on pure tone audiometry does not always reflect how a child hears in everyday life. This practice is inappropriate when evaluating the difficulties children experiencing auditory processing disorder (APD) in school or on the playground. Despite the marked increase in research on pediatric APD, there remains limited access to proper evaluation worldwide. This perspective article presents five common misconceptions of APD that contribute to inappropriate or limited management in children experiencing these deficits. The misconceptions discussed are (1) the disorder cannot be diagnosed due to the lack of a gold standard diagnostic test; (2) making generalizations based on profiles of children suspected of APD and not diagnosed with the disorder; (3) it is best to discard an APD diagnosis when another disorder is present; (4) arguing that the known link between auditory perception and higher cognition function precludes the validity of APD as a clinical entity; and (5) APD is not a clinical entity. These five misconceptions are described and rebutted using published data as well as critical thinking on current available knowledge on APD.

Cortical and Sensory Causes of Individual Differences in Selective Attention Ability Among Listeners With Normal Hearing Thresholds

PURPOSE

This review provides clinicians with an overview of recent findings relevant to understanding why listeners with normal hearing thresholds (NHTs) sometimes suffer from communication difficulties in noisy settings.

METHOD

The results from neuroscience and psychoacoustics are reviewed.

RESULTS

In noisy settings, listeners focus their attention by engaging cortical brain networks to suppress unimportant sounds; they then can analyze and understand an important sound, such as speech, amidst competing sounds. Differences in the efficacy of top-down control of attention can affect communication abilities. In addition, subclinical deficits in sensory fidelity can disrupt the ability to perceptually segregate sound sources, interfering with selective attention, even in listeners with NHTs. Studies of variability in control of attention and in sensory coding fidelity may help to isolate and identify some of the causes of communication disorders in individuals presenting at the clinic with "normal hearing."

CONCLUSIONS

How well an individual with NHTs can understand speech amidst competing sounds depends not only on the sound being audible but also on the integrity of cortical control networks and the fidelity of the representation of suprathreshold sound. Understanding the root cause of difficulties experienced by listeners with NHTs ultimately can lead to new, targeted interventions that address specific deficits affecting communication in noise.

PRESENTATION VIDEO

http://cred.pubs.asha.org/article.aspx?articleid=2601617.

Involvement of the Serotonin Transporter Gene in Accurate Subcortical Speech Encoding

A flourishing line of evidence has highlighted the encoding of speech sounds in the subcortical auditory system as being shaped by acoustic, linguistic, and musical experience and training. And while the heritability of auditory speech as well as nonspeech processing has been suggested, the genetic determinants of subcortical speech processing have not yet been uncovered. Here, we postulated that the serotonin transporter-linked polymorphic region (5-HTTLPR), a common functional polymorphism located in the promoter region of the serotonin transporter gene (SLC6A4), is implicated in speech encoding in the human subcortical auditory pathway. Serotonin has been shown as essential for modulating the brain response to sound both cortically and subcortically, yet the genetic factors regulating this modulation regarding speech sounds have not been disclosed. We recorded the frequency following response, a biomarker of the neural tracking of speech sounds in the subcortical auditory pathway, and cortical evoked potentials in 58 participants elicited to the syllable /ba/, which was presented >2000 times. Participants with low serotonin transporter expression had higher signal-to-noise ratios as well as a higher pitch strength representation of the periodic part of the syllable than participants with medium to high expression, possibly by tuning synaptic activity to the stimulus features and hence a more efficient suppression of noise. These results imply the 5-HTTLPR in subcortical auditory speech encoding and add an important, genetically determined layer to the factors shaping the human subcortical response to speech sounds.

SIGNIFICANCE STATEMENT

The accurate encoding of speech sounds in the subcortical auditory nervous system is of paramount relevance for human communication, and it has been shown to be altered in different disorders of speech and auditory processing. Importantly, this encoding is plastic and can therefore be enhanced by language and music experience. Whether genetic factors play a role in speech encoding at the subcortical level remains unresolved. Here we show that a common polymorphism in the serotonin transporter gene relates to an accurate and robust neural tracking of speech stimuli in the subcortical auditory pathway. This indicates that serotonin transporter expression, eventually in combination with other polymorphisms, delimits the extent to which lifetime experience shapes the subcortical encoding of speech.

Perspectives of Dutch health professionals regarding auditory processing disorders; a focus group study

OBJECTIVE

This study investigated the perspectives of professionals from the Dutch audiological centres on the definition and care pathways of children with suspected auditory processing disorders (susAPD).

DESIGN

focus group interviews.

STUDY SAMPLE

In total, 45 professionals from 6 disciplines, representing 22 different audiological centres and one ambulatory service, participated in five parallel focus group interviews. Participants had a variety of experience in diagnosing and advising children with suspected APD.

RESULTS

Qualitative analysis (open and thematic) identified four themes ("Definition", "Causes", "Diagnostic Procedures" and "Clinical Reasoning") expressing a variety of perspectives. Differences in perspectives were mainly affected by two debates: (1) whether or not APD exists as a pure (auditory) disorder and (2) whether or not current AP-tests are suitable in diagnosing children with listening difficulties. They also expressed a need for more guidance from the literature in their clinical decision making process.

CONCLUSIONS

Professionals from the Dutch audiological centres share a broad perspective on children with APD. The ICF framework supports this perspective, thereby diminishing the need for a clear definition. The use of AP-tests should be limited to children where broader developmental disorders are first ruled out; a possible "pure" APD could then be diagnosed in a limited number of children.

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.

Effects of an Auditory Lateralization Training in Children Suspected to Central Auditory Processing Disorder

Background and Objectives

Central auditory processing disorder [(C)APD] refers to a deficit in auditory stimuli processing in nervous system that is not due to higher-order language or cognitive factors. One of the problems in children with (C)APD is spatial difficulties which have been overlooked despite their significance. Localization is an auditory ability to detect sound sources in space and can help to differentiate between the desired speech from other simultaneous sound sources. Aim of this research was investigating effects of an auditory lateralization training on speech perception in presence of noise/competing signals in children suspected to (C)APD.

Subjects and Methods

In this analytical interventional study, 60 children suspected to (C)APD were selected based on multiple auditory processing assessment subtests. They were randomly divided into two groups: control (mean age 9.07) and training groups (mean age 9.00). Training program consisted of detection and pointing to sound sources delivered with interaural time differences under headphones for 12 formal sessions (6 weeks). Spatial word recognition score (WRS) and monaural selective auditory attention test (mSAAT) were used to follow the auditory lateralization training effects.

Results

This study showed that in the training group, mSAAT score and spatial WRS in noise (p value≤0.001) improved significantly after the auditory lateralization training.

Conclusions

We used auditory lateralization training for 6 weeks and showed that auditory lateralization can improve speech understanding in noise significantly. The generalization of this results needs further researches.

Maturation of the Central Auditory Nervous System in Children with Auditory Processing Disorder

Neurodevelopmental delay has been proposed as the underlying cause of the majority of cases of auditory processing disorder (APD). The current study employs the cortical auditory evoked potential (CAEP) to assess if maturational differences of the central auditory nervous system (CANS) can be identified between children who do and do not meet the diagnostic criterion for APD. The P1-N1 complex of the CAEP has previously been used for tracking development of the CANS in children with hearing impairment. Twenty-seven children (7 to 12 years old) who failed an APD behavioral test battery were age-matched (within 3 months) to children who had passed the same battery. CAEP responses to 500-Hz tone burst stimuli were recorded and analyzed for latency and amplitude measures. The P1-N1 complex of the CAEP, which has previously been used for tracking development of the CANS in children with hearing impairment, showed significant group differences. The children diagnosed with APD showed significantly increased latency (∼10 milliseconds) and significantly reduced amplitude (∼10 μV) of the early components of the CAEP compared with children with normal auditory processing. No significant differences were seen in the later P2 wave. The normal developmental course is for a decrease in latency and increase in amplitude as a function of age. The results of this study are, therefore, consistent with an immaturity of the CANS as an underlying cause of APD in children.

Characteristics of Auditory Processing Disorders: A Systematic Review

PURPOSE

The purpose of this review article is to describe characteristics of auditory processing disorders (APD) by evaluating the literature in which children with suspected or diagnosed APD were compared with typically developing children and to determine whether APD must be regarded as a deficit specific to the auditory modality or as a multimodal deficit.

METHOD

Six electronic databases were searched for peer-reviewed studies investigating children with (suspected) APD in comparison with typically developing peers. Relevant studies were independently reviewed and appraised by 2 reviewers. Methodological quality was quantified using the American Speech-Language-Hearing Association's levels of evidence.

RESULTS

Fifty-three relevant studies were identified. Five studies were excluded because of weak internal validity. In total, 48 studies were included, of which only 1 was classified as having strong methodological quality. Significant dissimilarities were found between children referred with listening difficulties and controls. These differences relate to auditory and visual functioning, cognition, language, reading, and physiological and neuroimaging measures.

CONCLUSIONS

Methodological quality of most of the incorporated studies was rated moderate due to the heterogeneous groups of participants, inadequate descriptions of participants, and the omission of valid and reliable measurements. The listening difficulties of children with APD may be a consequence of cognitive, language, and attention issues rather than bottom-up auditory processing.

Heritability of non-speech auditory processing skills

Recent insight into the genetic bases for autism spectrum disorder, dyslexia, stuttering, and language disorders suggest that neurogenetic approaches may also reveal at least one etiology of auditory processing disorder (APD). A person with an APD typically has difficulty understanding speech in background noise despite having normal pure-tone hearing sensitivity. The estimated prevalence of APD may be as high as 10% in the pediatric population, yet the causes are unknown and have not been explored by molecular or genetic approaches. The aim of our study was to determine the heritability of frequency and temporal resolution for auditory signals and speech recognition in noise in 96 identical or fraternal twin pairs, aged 6-11 years. Measures of auditory processing (AP) of non-speech sounds included backward masking (temporal resolution), notched noise masking (spectral resolution), pure-tone frequency discrimination (temporal fine structure sensitivity), and nonsense syllable recognition in noise. We provide evidence of significant heritability, ranging from 0.32 to 0.74, for individual measures of these non-speech-based AP skills that are crucial for understanding spoken language. Identification of specific heritable AP traits such as these serve as a basis to pursue the genetic underpinnings of APD by identifying genetic variants associated with common AP disorders in children and adults.

Auditory processing disorders with and without central auditory discrimination deficits

Auditory processing disorder (APD) is defined as a processing deficit in the auditory modality and spans multiple processes. To date, APD diagnosis is mostly based on the utilization of speech material. Adequate nonspeech tests that allow differentiation between an actual central hearing disorder and related disorders such as specific language impairments are still not adequately available. In the present study, 84 children between 6 and 17 years of age (clinical group), referred to three audiological centers for APD diagnosis, were evaluated with standard audiological tests and additional auditory discrimination tests. Latter tests assessed the processing of basic acoustic features at two different stages of the ascending central auditory system: (1) auditory brainstem processing was evaluated by quantifying interaural frequency, level, and signal duration discrimination (interaural tests). (2) Diencephalic/telencephalic processing was assessed by varying the same acoustic parameters (plus signals with sinusoidal amplitude modulation), but presenting the test signals in conjunction with noise pulses to the contralateral ear (dichotic(signal/noise) tests). Data of children in the clinical group were referenced to normative data obtained from more than 300 normally developing healthy school children. The results in the audiological and the discrimination tests diverged widely. Of the 39 children that were diagnosed with APD in the audiological clinic, 30 had deficits in auditory performance. Even more alarming was the fact that of the 45 children with a negative APD diagnosis, 32 showed clear signs of a central hearing deficit. Based on these results, we suggest revising current diagnostic procedure to evaluate APD in order to more clearly differentiate between central auditory processing deficits and higher-order (cognitive and/or language) processing deficits.

The relation between working memory capacity and auditory lateralization in children with auditory processing disorders

OBJECTIVE

Auditory processing disorder (APD) describes a complex and heterogeneous disorder characterized by poor speech perception, especially in noisy environments. APD may be responsible for a range of sensory processing deficits associated with learning difficulties. There is no general consensus about the nature of APD and how the disorder should be assessed or managed. This study assessed the effect of cognition abilities (working memory capacity) on sound lateralization in children with auditory processing disorders, in order to determine how "auditory cognition" interacts with APD.

METHODS

The participants in this cross-sectional comparative study were 20 typically developing and 17 children with a diagnosed auditory processing disorder (9-11 years old). Sound lateralization abilities investigated using inter-aural time (ITD) differences and inter-aural intensity (IID) differences with two stimuli (high pass and low pass noise) in nine perceived positions. Working memory capacity was evaluated using the non-word repetition, and forward and backward digits span tasks. Linear regression was employed to measure the degree of association between working memory capacity and localization tests between the two groups.

RESULTS

Children in the APD group had consistently lower scores than typically developing subjects in lateralization and working memory capacity measures. The results showed working memory capacity had significantly negative correlation with ITD errors especially with high pass noise stimulus but not with IID errors in APD children.

CONCLUSIONS

The study highlights the impact of working memory capacity on auditory lateralization. The finding of this research indicates that the extent to which working memory influences auditory processing depend on the type of auditory processing and the nature of stimulus/listening situation.

Influence of memory, attention, IQ and age on auditory temporal processing tests: preliminary study

PURPOSE

To investigate the existence of correlations between the performance of children in auditory temporal tests (Frequency Pattern and Gaps in Noise--GIN) and IQ, attention, memory and age measurements.

METHOD

Fifteen typically developing individuals between the ages of 7 to 12 years and normal hearing participated in the study. Auditory temporal processing tests (GIN and Frequency Pattern), as well as a Memory test (Digit Span), Attention tests (auditory and visual modality) and intelligence tests (RAVEN test of Progressive Matrices) were applied.

RESULTS

Significant and positive correlation between the Frequency Pattern test and age variable were found, which was considered good (p<0.01, 75.6%). There were no significant correlations between the GIN test and the variables tested.

CONCLUSIONS

Auditory temporal skills seem to be influenced by different factors: while the performance in temporal ordering skill seems to be influenced by maturational processes, the performance in temporal resolution was not influenced by any of the aspects investigated.

Beyond DSM: the role of auditory processing in attention and its disorders

This article reviews and synthesizes recent research regarding auditory processing, attention, and their roles in generating both adaptive and maladaptive behavioral responses. Research in these areas is beginning to converge on the role of polymorphisms associated with catecholamine metabolism and transport, particularly the neurotransmitter dopamine. The synthesis offered in this article appears to be the first to argue that genetic differences in dopamine metabolism may be the common factor in four disparate disorders that are often observed to be comorbid, i.e., attention-deficit hyperactivity disorder, auditory processing disorders, developmental language disorders, and reading disorders.

A maximum-likelihood procedure for estimating psychometric functions: thresholds, slopes, and lapses of attention

Green [J. Acoust. Soc. Am. 87, 2662-2674 (1990)] suggested an efficient, maximum-likelihood-based approach for adaptively estimating thresholds. Such procedures determine the signal strength on each trial by first identifying the most likely psychometric functions among the pre-proposed alternatives based on responses from previous trials, and then finding the signal strength at the "sweet point" on that most likely function. The sweet point is the point on the psychometric function that is associated with the minimum expected variance. Here, that procedure is extended to reduce poor estimates that result from lapses in attention. The sweet points for the threshold, slope, and lapse parameters of a transformed logistic psychometric function are derived. In addition, alternative stimulus placement algorithms are considered. The result is a relatively fast and robust estimation of a three-parameter psychometric function.

Efficacy of Auditory Interventions for Central Auditory Processing Disorder: A Response to Fey et al. (2011)

Purpose

To provide a commentary on “Auditory Processing Disorder and Auditory/Language Interventions: An Evidence-Based Systematic Review” by Fey et al. (2011).

Method

Examination of the conclusions drawn by Fey et al. (2011) in the context of the American Academy of Audiology (2010a, 2010b) and American Speech-Language-Hearing Association (2005a, 2005b, 2005c) guidelines for the diagnosis and treatment of auditory processing disorder, the evidence cited therein, and other pertinent published reports.

Results

The review provided by Fey et al. (2011) is limited due to the exclusion of pertinent efficacy studies from their analysis, inclusion of studies that did not employ strictly auditory-based therapies, and lack of well-defined experimental groups in many of the studies cited. Further, the questions posed by their literature review may not have addressed the efficacy of true auditory interventions in the remediation of auditory difficulties in children who have primary deficits in central auditory processing.

Conclusion

A more comprehensive review than that done by Fey et al. (2011) would have better addressed the fundamental question of the efficacy of direct remediation activities for children with central auditory processing disorder.