Publications by authors named "Frank Musiek"

57 Publications

Behavioral and Hemodynamic Changes Following Dichotic Training in Patients with Neurological Deficits of the Auditory Nervous System: A Case Series.

J Am Acad Audiol 2021 Mar 4. Epub 2021 Mar 4.

Department of Otolaryngology - Head and Neck Surgery, University of Kentucky, Lexington, Kentucky.

Background:  Dichotic listening occurs when one attends to different acoustical messages presented simultaneously to both ears. This is important for understanding speech in compromised listening situations, such as background noise. Deficits in dichotic listening can be remediated by participating in auditory training. We present two patients with binaural integration deficits who underwent dichotic interaural intensity difference (DIID) training.

Purpose:  The purpose of this investigation is to demonstrate improvement of dichotic listening deficits following DIID training in neurological patients seen clinically for hearing issues.

Research Design:  This was a case series utilizing a pre- and posttreatment design.

Study Sample:  This case series utilized two female participants who demonstrated binaural integration deficits during an auditory processing evaluation.

Intervention:  The participants underwent a pretraining auditory processing evaluation and functional magnetic resonance imaging (fMRI). Participants then underwent 12, 30-minute DIID training sessions followed by posttreatment auditory processing evaluations and fMRI.

Data Collection And Analysis:  Data was collected at the pretreatment appointment and then immediately following the completion of the training.

Results:  Each patient demonstrated varying degrees of improvement on the posttreatment assessment. Case 1 showed significant improvement on the Speech-in-Noise-Revised (SPIN-R) test. fMRI showed changes in activation patterns following training. Case 2 demonstrated improved scores on the Dichotic Digits Test and SPIN-R and increased activation of the calcarine sulcus following training.

Conclusion:  Dichotic training can be an efficacious treatment for binaural integration deficits and may show evidence of improving speech understanding in noise. This case series demonstrates a promising therapy to help patients improve auditory function by improving dichotic listening skills.
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http://dx.doi.org/10.1055/s-0040-1719095DOI Listing
March 2021

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

Front Neurol 2019 18;10:1096. Epub 2019 Oct 18.

Neuroaudiology Lab, University of Arizona, Tucson, AZ, United States.

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.
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http://dx.doi.org/10.3389/fneur.2019.01096DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6813210PMC
October 2019

Evidence for a dynorphin-mediated inner ear immune/inflammatory response and glutamate-induced neural excitotoxicity: an updated analysis.

J Neurophysiol 2019 10 24;122(4):1421-1460. Epub 2019 Jul 24.

Department of Speech, Language, and Hearing Sciences, University of Arizona, Tucson, Arizona.

Acoustic overstimulation (AOS) is defined as the stressful overexposure to high-intensity sounds. AOS is a precipitating factor that leads to a glutamate (GLU)-induced Type I auditory neural excitotoxicity and an activation of an immune/inflammatory/oxidative stress response within the inner ear, often resulting in cochlear hearing loss. The dendrites of the Type I auditory neural neurons that innervate the inner hair cells (IHCs), and respond to the IHC release of the excitatory neurotransmitter GLU, are themselves directly innervated by the dynorphin (DYN)-bearing axon terminals of the descending brain stem lateral olivocochlear (LOC) system. DYNs are known to increase GLU availability, potentiate GLU excitotoxicity, and induce superoxide production. DYNs also increase the production of proinflammatory cytokines by modulating immune/inflammatory signal transduction pathways. Evidence is provided supporting the possibility that the GLU-mediated Type I auditory neural dendritic swelling, inflammation, excitotoxicity, and cochlear hearing loss that follow AOS may be part of a brain stem-activated, DYN-mediated cascade of inflammatory events subsequent to a LOC release of DYNs into the cochlea. In support of a DYN-mediated cascade of events are established investigations linking DYNs to the immune/inflammatory/excitotoxic response in other neural systems.
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http://dx.doi.org/10.1152/jn.00595.2018DOI Listing
October 2019

GIN Test: A Meta-Analysis on Its Neurodiagnostic Value.

J Am Acad Audiol 2020 02 1;31(2):147-157. Epub 2019 Jul 1.

Speech, Language, and Hearing Department, University of Arizona, Tucson, AZ.

Purpose: A meta-analysis was conducted to evaluate how effective the Gaps-in-Noise (GIN) test is in separating populations who are and who are not at risk of having neurological damage related to the central auditory nervous system (CANS). This was investigated by asking three specific questions: (1) Does ear and side of lesion have an effect over the individual's performance? (2) How large is the difference in performance between control and neurological groups? (3) What are the diagnostic indices related to the GIN test?

Data Collection And Analysis: A literature review was performed between April 2016 and April 2017. The eligibility criteria for inclusion were as follows: (1) studies that used the GIN test as an outcome measure, (2) studies that included adult participants who either had confirmed lesions or were at risk of having lesions to the CANS or related regions, and (3) studies that had a neurologically normal control group. From relevant studies that met eligibility criteria, information regarding study design, participants, lesion details and origins, use of additional assessments, GIN performance scores for both control (CTRL) and neurological (NRLG) groups, GIN cutoff scores and proportion of individuals with normal and abnormal performances were all included.

Results: Nine studies were included, totaling 221 participants in NRLG (stroke = 90, epilepsy = 67, and blast exposure [BLST] = 64) and 262 in CTRL (Stroke = 106, Epilepsy = 98, and BLST = 58). No significant ear effects related to side of lesion were observed for the GIN test in neurological patients nor were there significant ear differences for normal individuals with symmetrically normal hearing. The GIN demonstrated consistency among different neurological populations, presented good sensitivity and specificity rates, and was overall accurate in discriminating between participants with neuroauditory lesions from neurologically normal individuals.

Conclusions: The GIN is thus a clinically effective measure that provides insight into the CANS integrity and may aid in clinical diagnosis by distinguishing between populations who are and who are not at risk of having neurological damage affecting the CANS.
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http://dx.doi.org/10.3766/jaaa.18079DOI Listing
February 2020

Central deafness: a review of past and current perspectives.

Int J Audiol 2019 10 8;58(10):605-617. Epub 2019 May 8.

Speech, Language and Hearing Sciences, University of Arizona , Tucson , AZ , USA.

The purpose of this review was to describe and differentiate clinical syndromes caused by lesions of the central auditory nervous system (CANS). Relevant literature was identified through Pubmed and Google Scholar searches using the key terms: central deafness, auditory agnosia, word deafness and cortical deafness. Given the authors' intent to review past and current perspectives on central deafness, no publication date range was imposed. The review is organised around complete central deafness (CCD), central deafness (CD), word deafness and nonverbal agnosia (NVA), including anatomy and pathophysiology, symptom profile and audiological findings. Four case studies are presented to demonstrate the clinical correlates of CD. Central deafness is a rare condition typically resulting from bilateral compromise of the CANS. The closer to the auditory cortex bilateral lesions are located, the greater the probability of CD. A variety of symptoms present with or appear subsequent to CD, including tinnitus, hallucinations, voice changes and hypersensitivity to sounds (if heard by the patient), as well as diverse neurological symptoms depending on the non-auditory areas of the brain that may also be involved. Thorough and appropriate audiological testing is critical to accurately diagnose CD and its variants.
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http://dx.doi.org/10.1080/14992027.2019.1606458DOI Listing
October 2019

A Response to "The Mystery of Unexplained Variance-Some Comments on Brenneman et al (2017)".

J Am Acad Audiol 2019 09 8;30(8):735. Epub 2019 Mar 8.

University of Louisville.

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http://dx.doi.org/10.3766/jaaa.18033DOI Listing
September 2019

Enhancement of the Auditory Late Response (N1-P2) by Presentation of Stimuli From an Unexpected Location.

J Am Acad Audiol 2019 06 23;30(6):451-458. Epub 2018 Nov 23.

School of Medicine, University of Louisville, Louisville, KY.

Background: Passive electrophysiological protocols, such as the middle latency response and speech auditory brainstem response, are often advocated in the objective assessment of central auditory processing disorder (CAPD). However, few established electrophysiological protocols exist for CAPD assessment that have patients participate in active tasks which more closely approximate real-world listening. To this end, the present study used a discrimination task (i.e., oddball paradigm) to measure an enhancement of the auditory late response (N1-P2) that occurs when participants direct their auditory attention toward speech arising from an unexpected spatial location.

Purpose: To establish whether N1-P2 is enhanced when auditory attention is directed toward an unexpected location during a two-word discrimination task. In addition, it was also investigated whether any enhancements in this response were contingent on the stimulus being counted as part of the oddball paradigm.

Research Design: Prospective study with a repeated measures design.

Study Sample: Ten normal hearing adults, with an age range of 18-24 years.

Data Collection And Analysis: The N1 and P2 latencies and peak-to-peak amplitudes were recorded during a P300 paradigm. A series of repeated measures of analysis of variance and a correlation analysis was performed.

Results: There was a significant effect of stimulus location, in which words arising from the unexpected location showed a larger N1-P2 peak-to-peak amplitude and an earlier N1 latency. This effect was seen regardless of whether or not participants had to count the word total in memory.

Conclusions: These findings suggest that spatial enhancement of the N1-P2 is a fairly robust phenomenon in normal hearing adult listeners. Additional studies are needed to determine whether this enhancement is absent or reduced in patients with CAPD.
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http://dx.doi.org/10.3766/jaaa.17047DOI Listing
June 2019

The Middle Latency Response: A Review of Findings in Various Central Nervous System Lesions.

J Am Acad Audiol 2018 10;29(9):855-867

Connecticut Children's Medical Center, Hartford, CT.

Background: The middle latency response (MLR) first came to light as an auditory evoked potential in 1958. Since then, it has aroused substantial interest and investigation by clinicians and researchers alike. In recent history, its use and popularity have dwindled in tandem with various other auditory evoked potentials in audiology. One area for which MLR research and application has been overlooked is its potential value in measuring the neural integrity of the auditory thalamocortical pathway. In a broader sense, the MLR, when combined with the auditory brain stem response, can provide information concerning the status of much of the central auditory system pathways. This review is intended to provide information concerning the MLR as a measure of central auditory function for the reader to consider.

Purpose: To review and synthesize the scientific literature regarding the potential value of the MLR in assessing the integrity of the central auditory system and to provide the reader an informed perspective on the value of the MLR in this regard. Information is also provided on the MLR generator sites and fundamental characteristics of this evoked potential essential to its clinical and or research application.

Research Design: A systematic review and synthesis of the literature focusing on the MLR and lesions of the central auditory system.

Study Sample: Studies and individual cases were reviewed and analyzed that evidenced documented lesions of the central auditory nervous system.

Data Collection And Analysis: The authors searched and reviewed the literature (journal articles, book chapters, and books) pertaining to central auditory system lesion effects on the MLR.

Results: Although findings varied from study to study, overall, the MLR was reasonably sensitive and specific to neurological compromise of the central auditory system. This finding is consistent with the generator sites of this evoked potential.

Conclusions: The MLR is a valuable tool for assessing the integrity of the central auditory system. It should be of interest to the clinician or researcher who focuses their attention on the function and dysfunction of the higher auditory system.
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http://dx.doi.org/10.3766/jaaa.16141DOI Listing
October 2018

The Relationship between Central Auditory Processing, Language, and Cognition in Children Being Evaluated for Central Auditory Processing Disorder.

J Am Acad Audiol 2017 Sep;28(8):758-769

Department of Otolaryngology-Head and Neck Surgery and Communicative Disorders, University of Louisville School of Medicine, Louisville, KY.

Background: Pediatric central auditory processing disorder (CAPD) is frequently comorbid with other childhood disorders. However, few studies have examined the relationship between commonly used CAPD, language, and cognition tests within the same sample.

Purpose: The present study examined the relationship between diagnostic CAPD tests and "gold standard" measures of language and cognitive ability, the Clinical Evaluation of Language Fundamentals (CELF) and the Wechsler Intelligence Scale for Children (WISC).

Research Design: A retrospective study.

Study Sample: Twenty-seven patients referred for CAPD testing who scored average or better on the CELF and low average or better on the WISC were initially included. Seven children who scored below the CELF and/or WISC inclusion criteria were then added to the dataset for a second analysis, yielding a sample size of 34.

Data Collection And Analysis: Participants were administered a CAPD battery that included at least the following three CAPD tests: Frequency Patterns (FP), Dichotic Digits (DD), and Competing Sentences (CS). In addition, they were administered the CELF and WISC. Relationships between scores on CAPD, language (CELF), and cognition (WISC) tests were examined using correlation analysis.

Results: DD and FP showed significant correlations with Full Scale Intelligence Quotient, and the DD left ear and the DD interaural difference measures both showed significant correlations with working memory. However, ∼80% or more of the variance in these CAPD tests was unexplained by language and cognition measures. Language and cognition measures were more strongly correlated with each other than were the CAPD tests with any CELF or WISC scale. Additional correlations with the CAPD tests were revealed when patients who scored in the mild-moderate deficit range on the CELF and/or in the borderline low intellectual functioning range on the WISC were included in the analysis.

Conclusions: While both the DD and FP tests showed significant correlations with one or more cognition measures, the majority of the variance in these CAPD measures went unexplained by cognition. Unlike DD and FP, the CS test was not correlated with cognition. Additionally, language measures were not significantly correlated with any of the CAPD tests. Our findings emphasize that the outcomes and interpretation of results vary as a function of the subject inclusion criteria that are applied for the CELF and WISC. Including participants with poorer cognition and/or language scores increased the number of significant correlations observed. For this reason, it is important that studies investigating the relationship between CAPD and other domains or disorders report the specific inclusion criteria used for all tests.
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http://dx.doi.org/10.3766/jaaa.16119DOI Listing
September 2017

Perspectives on the Pure-Tone Audiogram.

J Am Acad Audiol 2017 Jul/Aug;28(7):655-671

University College London Hospitals, London, UK.

Background: The pure-tone audiogram, though fundamental to audiology, presents limitations, especially in the case of central auditory involvement. Advances in auditory neuroscience underscore the considerably larger role of the central auditory nervous system (CANS) in hearing and related disorders. Given the availability of behavioral audiological tests and electrophysiological procedures that can provide better insights as to the function of the various components of the auditory system, this perspective piece reviews the limitations of the pure-tone audiogram and notes some of the advantages of other tests and procedures used in tandem with the pure-tone threshold measurement.

Purpose: To review and synthesize the literature regarding the utility and limitations of the pure-tone audiogram in determining dysfunction of peripheral sensory and neural systems, as well as the CANS, and to identify other tests and procedures that can supplement pure-tone thresholds and provide enhanced diagnostic insight, especially regarding problems of the central auditory system.

Research Design: A systematic review and synthesis of the literature.

Data Collection And Analysis: The authors independently searched and reviewed literature (journal articles, book chapters) pertaining to the limitations of the pure-tone audiogram.

Results: The pure-tone audiogram provides information as to hearing sensitivity across a selected frequency range. Normal or near-normal pure-tone thresholds sometimes are observed despite cochlear damage. There are a surprising number of patients with acoustic neuromas who have essentially normal pure-tone thresholds. In cases of central deafness, depressed pure-tone thresholds may not accurately reflect the status of the peripheral auditory system. Listening difficulties are seen in the presence of normal pure-tone thresholds. Suprathreshold procedures and a variety of other tests can provide information regarding other and often more central functions of the auditory system.

Conclusions: The audiogram is a primary tool for determining type, degree, and configuration of hearing loss; however, it provides the clinician with information regarding only hearing sensitivity, and no information about central auditory processing or the auditory processing of real-world signals (i.e., speech, music). The pure-tone audiogram offers limited insight into functional hearing and should be viewed only as a test of hearing sensitivity. Given the limitations of the pure-tone audiogram, a brief overview is provided of available behavioral tests and electrophysiological procedures that are sensitive to the function and integrity of the central auditory system, which provide better diagnostic and rehabilitative information to the clinician and patient.
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http://dx.doi.org/10.3766/jaaa.16061DOI Listing
May 2018

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

Int J Audiol 2017 07 28;56(7):499-506. Epub 2017 Feb 28.

d Neuroaudiology Lab , University of Arizona , Tucson , AZ , USA.

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.
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http://dx.doi.org/10.1080/14992027.2017.1284351DOI Listing
July 2017

Auditory Training for Central Auditory Processing Disorder.

Semin Hear 2015 Nov;36(4):199-215

Speech, Language and Hearing Sciences, the University of Arizona, Tucson, Arizona.

Auditory training (AT) is an important component of rehabilitation for patients with central auditory processing disorder (CAPD). The present article identifies and describes aspects of AT as they relate to applications in this population. A description of the types of auditory processes along with information on relevant AT protocols that can be used to address these specific deficits is included. Characteristics and principles of effective AT procedures also are detailed in light of research that reflects on their value. Finally, research investigating AT in populations who show CAPD or present with auditory complaints is reported. Although efficacy data in this area are still emerging, current findings support the use of AT for treatment of auditory difficulties.
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http://dx.doi.org/10.1055/s-0035-1564458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4910543PMC
November 2015

Auditory Impairments in HIV-Infected Children.

Ear Hear 2016 Jul-Aug;37(4):443-51

1DarDar Health Study, Dar es Salaam, Tanzania; 2Geisel School of Medicine, Department of Medicine, Hanover, New Hampshire, USA; 3Creare, LLC, Hanover, New Hampshire, USA; 4Harvard Medical School, Boston, Massachusetts, USA; 5Muhimbili University of Health and Allied Sciences, Department of Otolaryngology, Dar es Salaam, Tanzania; and 6University of Arizona, Department of Speech, Language, and Hearing Sciences, Tucson, Arizona, USA.

Objectives: In a cross-sectional study of human immunodeficiency virus (HIV)-infected adults, the authors showed lower distortion product otoacoustic emissions (DPOAEs) in HIV+ individuals compared with controls as well as findings consistent with a central auditory processing deficit in HIV+ adults on antiretroviral therapy. The authors hypothesized that HIV+ children would also have a higher prevalence of abnormal central and peripheral hearing test results compared with HIV- controls.

Design: Pure-tone thresholds, DPOAEs, and tympanometry were performed on 244 subjects (131 HIV+ and 113 HIV- subjects). Thirty-five of the HIV+, and 3 of the HIV- subjects had a history of tuberculosis treatment. Gap detection results were available for 18 HIV- and 44 HIV+ children. Auditory brainstem response results were available for 72 HIV- and 72 HIV+ children. Data from ears with abnormal tympanograms were excluded.

Results: HIV+ subjects were significantly more likely to have abnormal tympanograms, histories of ear drainage, tuberculosis, or dizziness. All audiometric results were compared between groups using a two-way ANOVA with HIV status and ear drainage history as grouping variables. Mean audiometric thresholds, gap detection thresholds, and auditory brainstem response latencies did not differ between groups, although the HIV+ group had a higher proportion of individuals with a hearing loss >25 dB HL in the better ear. The HIV+ group had reduced DPOAE levels (p < 0.05) at multiple frequencies compared with HIV- subjects. No relationships were found between treatment regimens or delay in starting treatment and audiological parameters.

Conclusions: As expected, children with HIV+ were more likely to have a history of ear drainage, and to have abnormal tympanograms. Similar to the adult findings, the HIV+ group did not show significantly reduced audiometric thresholds, but did have significantly lower DPOAE magnitudes. These data suggest that (1) HIV+ children often have middle ear damage which complicates understanding the direct effects of HIV on the hearing system, and (2) even when corrected for confounders DPOAEs were lower in the HIV+ group. Previous studies suggest ototoxicity from antiretroviral drugs is an unlikely cause of the reduced DPOAE magnitudes. Other possibilities include effects on efferent pathways connecting to outer hair cells or a direct effect of HIV on the cochlea.
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http://dx.doi.org/10.1097/AUD.0000000000000276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4925260PMC
January 2018

Characteristics of Pediatric Performance on a Test Battery Commonly Used in the Diagnosis of Central Auditory Processing Disorder.

J Am Acad Audiol 2015 Jul-Aug;26(7):652-69

Department of Speech, Language, and Hearing Sciences, University of Connecticut, Storrs, CT.

Background: Although central auditory processing disorder (CAPD) test battery performance has been examined in adults with neurologic lesions of the central auditory nervous system (CANS), similar data on children being referred for CAPD evaluations are sparse.

Purpose: This study characterizes CAPD test battery performance in children using tests commonly administered to diagnose the disorder. Specifically, this study describes failure rates for various test combinations, relationships between CAPD tests used in the battery, and the influence of cognitive function on CAPD test performance and CAPD diagnosis. A comparison is also made between the performance of children with CAPD and data from patients with neurologic lesions of the CANS.

Research Design: A retrospective study.

Study Sample: Fifty-six pediatric patients were referred for CAPD testing.

Data Collection And Analysis: Participants were administered four CAPD tests, including frequency patterns (FP), low-pass filtered speech (LPFS), dichotic digits (DD), and competing sentences (CS). In addition, they were given the Wechsler Intelligence Scale for Children (WISC). Descriptive analyses examined the failure rates of various test combinations, as well as how often children with CAPD failed certain combinations when compared with adults with CANS lesions. A principal components analysis was performed to examine interrelationships between tests. Correlations and regressions were conducted to determine the relationship between CAPD test performance and the WISC.

Results: Results showed that the FP and LPFS tests were most commonly failed by children with CAPD. Two-test combinations that included one or both of these two tests and excluded DD tended to be failed more often. Including the DD and CS test in a battery benefited specificity. Tests thought to measure interhemispheric transfer tended to be correlated. Compared with adult patients with neurologic lesions, children with CAPD tended to fail LPFS more frequently and DD less frequently. Both groups failed FP with relatively equal frequency.

Conclusions: The two-test combination that showed the highest failure rate for children with CAPD was LPFS-FP. Comparison with adults with CANS lesions, however, suggests that the mechanisms underlying LPFS performance in children need to be better understood. The two-test combination that showed the next highest failure rates among children with CAPD and did not include LPFS was CS-FP. If it is desirable to use a dichotic measure that has a lower linguistic load than CS then DD can be substituted for CS despite the slightly lower failure rate of the DD-FP battery.
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http://dx.doi.org/10.3766/jaaa.14108DOI Listing
January 2018

Psychophysical and behavioral peripheral and central auditory tests.

Handb Clin Neurol 2015 ;129:313-32

Department of Speech and Hearing Sciences, Washington State University Spokane, Spokane, WA, USA. Electronic address:

Diagnostic batteries to assess the integrity of the central auditory nervous system (CANS) include behavioral (i.e., psychophysical) tests, electrophysiologic procedures, and to some degree, electroacoustic procedures. In this chapter, we focus on behavioral tests used to identify lesions (including diffuse lesions), abnormalities, or dysfunction of the CANS, as well as identify associated functional deficits (e.g., listening in noise deficits). Following a brief review of several tests considered more peripheral in their application (e.g., pure-tone thresholds, otoacoustic emissions, acoustic reflex), we provide some historic context and a review of tests currently in use which are sensitized by design to measure central auditory function, as well as others which have not been adopted clinically and new tests and procedures which hold promise for clinical diagnosis. Tests reviewed include those of dichotic listening, temporal processing (e.g., temporal resolution and temporal patterning), binaural interaction (e.g., masking level differences), monaural low-redundancy measures (e.g., speech in noise or competition, filtered speech, time-compressed speech), and new paradigms which measure auditory evoked potentials in response to test stimuli typically used in behavioral tests.
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http://dx.doi.org/10.1016/B978-0-444-62630-1.00018-4DOI Listing
April 2015

Electrophysiological gap detection thresholds: effects of age and comparison with a behavioral measure.

J Am Acad Audiol 2014 Nov-Dec;25(10):999-1007

University of Connecticut, Storrs, CT.

Background: Temporal processing ability has been linked to speech understanding ability and older adults often complain of difficulty understanding speech in difficult listening situations. Temporal processing can be evaluated using gap detection procedures. There is some research showing that gap detection can be evaluated using an electrophysiological procedure. However, there is currently no research establishing gap detection threshold using the N1-P2 response.

Purpose: The purposes of the current study were to 1) determine gap detection thresholds in younger and older normal-hearing adults using an electrophysiological measure, 2) compare the electrophysiological gap detection threshold and behavioral gap detection threshold within each group, and 3) investigate the effect of age on each gap detection measure.

Design: This study utilized an older adult group and younger adult group to compare performance on an electrophysiological and behavioral gap detection procedure.

Study Sample: The subjects in this study were 11 younger, normal-hearing adults (mean = 22 yrs) and 11 older, normal-hearing adults (mean = 64.36 yrs).

Data Collection: All subjects completed an adaptive behavioral gap detection procedure in order to determine their behavioral gap detection threshold (BGDT). Subjects also completed an electrophysiologic gap detection procedure to determine their electrophysiologic gap detection threshold (EGDT).

Results: Older adults demonstrated significantly larger gap detection thresholds than the younger adults. However, EGDT and BGDT were not significantly different in either group. The mean difference between EGDT and BGDT for all subjects was 0.43 msec.

Conclusions: Older adults show poorer gap detection ability when compared to younger adults. However, this study shows that gap detection thresholds can be measured using evoked potential recordings and yield results similar to a behavioral measure.
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http://dx.doi.org/10.3766/jaaa.25.10.8DOI Listing
August 2015

The influence of aging on interaural asymmetries in middle latency response amplitude.

J Am Acad Audiol 2014 Apr;25(4):324-34

University of Connecticut, Department of Communication Sciences, Neuroaudiology Laboratory, Storrs, CT.

Background: Auditory-evoked potentials (EPs) provide a more objective assessment of central auditory nervous system (CANS) dysfunction when compared to behavioral measures because they do not require a behavioral response (Anderson and Kraus, 2010). In this regard, the middle latency response (MLR) has been considered an important component of CANS assessment (Jerger et al, 1988); however, its large within-group variability limits its usefulness (Musiek et al, 1999). It has been argued that performing intratest calculations on the MLR (e.g., difference in EP amplitude when stimulating the left ear versus the right ear) can reduce the within-group variability of the MLR and enhance its clinical usefulness (Musiek et al, 1999; Weihing et al, 2012). To date, it has not been investigated how well these MLR intratest measures reduce within-group variability in adults of various ages, nor has it been shown that these intratest measures are sensitive to aging-related changes in the CANS.

Purpose: The two primary goals of the present study were (1) to determine if calculating an intratest MLR measure, the difference in MLR Na-Pa peak-to-peak amplitude on left versus right ear stimulation (i.e., "ear effects"), will reduce within-group variability in adults of various ages; and (2) to determine if ear effect magnitude will change as a function of aging. Ear effects were measured in both quiet and in noise to determine if the addition of noise enhanced any age-related-effects.

Research Design: A cross-sectional study was conducted.

Study Sample: The researchers studied 30 adults ranging in age from 20-80 yr with hearing sensitivity of 25 dB HL or better at the octave frequencies from 500-2000 Hz, and no history of neurologic issues. Adults were assigned to one of three age groups based on their chronological age, which were young adults, middle-aged adults, and older adults.

Data Collection And Analysis: MLRs were acquired using a Nicolet Spirit 2000 during a single laboratory visit. To determine if within-group variability decreased significantly with ear effects, variability for absolute amplitude measures was compared to ear effect variability using the Pitman t-test. To examine potential effects of background noise and aging, data were analyzed using a mixed-factorial analysis of variance with the within-subjects factor "background noise" and the between-subjects factor "age group."

Results: Within-group variability was significantly reduced by calculating ear effects for the youngest group only. Additionally, the oldest adults in the present sample showed significantly larger ear effects than younger and middle-aged adults. This effect did not appear to be a result of differences in peripheral hearing sensitivity. Finally, introducing noise into the paradigm did not influence the observed effects.

Conclusions: Ear effects become larger in older adults possibly as a result of age-related changes in the subcortical and/or cortical generators of the MLR. Failure of the ear effect calculation to reduce within-group variability in the middle-aged and older adults suggests that interaural asymmetries in MLR amplitude become more variable across participants who are older than 50 yr. Information obtained from this measure may benefit the development of treatment plans for older adults with hearing difficulties.
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http://dx.doi.org/10.3766/jaaa.25.4.4DOI Listing
April 2014

Auditory impairments in HIV-infected individuals in Tanzania.

Ear Hear 2014 May-Jun;35(3):306-17

1DarDar Health Study, Dar es Salaam, Tanzania; 2Department of Otolaryngology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania; 3Creare, Inc., Hanover, New Hampshire, USA; 4Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA; 5Harvard Medical School, Boston, Massachusetts, USA; 6Department of Medicine, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania; and 7Department of Speech, Language and Hearing Sciences, University of Connecticut, Storrs, Connecticut, USA.

Objectives: Abnormal hearing tests have been noted in human immunodeficiency virus (HIV)-infected patients in several studies, but the nature of the hearing deficit has not been clearly defined. The authors performed a cross-sectional study of both HIV+ and HIV- individuals in Tanzania by using an audiological test battery. The authors hypothesized that HIV+ adults would have a higher prevalence of abnormal central and peripheral hearing test results compared with HIV- controls. In addition, they anticipated that the prevalence of abnormal hearing assessments would increase with antiretroviral therapy (ART) use and treatment for tuberculosis (TB).

Design: Pure-tone thresholds, distortion product otoacoustic emissions (DPOAEs), tympanometry, and a gap-detection test were performed using a laptop-based hearing testing system on 751 subjects (100 HIV- in the United States, plus 651 in Dar es Salaam, Tanzania, including 449 HIV+ [130 ART- and 319 ART+], and 202 HIV-, subjects. No U.S. subjects had a history of TB treatment. In Tanzania, 204 of the HIV+ and 23 of the HIV- subjects had a history of TB treatment. Subjects completed a video and audio questionnaire about their hearing, as well as a health history questionnaire.

Results: HIV+ subjects had reduced DPOAE levels compared with HIV- subjects, but their hearing thresholds, tympanometry results, and gap-detection thresholds were similar. Within the HIV+ group, those on ART reported significantly greater difficulties understanding speech in noise, and were significantly more likely to report that they had difficulty understanding speech than the ART- group. The ART+ group had a significantly higher mean gap-detection threshold compared with the ART- group. No effects of TB treatment were seen.

Conclusions: The fact that the ART+/ART- groups did not differ in measures of peripheral hearing ability (DPOAEs, thresholds), or middle ear measures (tympanometry), but that the ART+ group had significantly more trouble understanding speech and had higher gap-detection thresholds indicates a central processing deficit. These data suggest that: (1) hearing deficits in HIV+ individuals could be a CNS side effect of HIV infection, (2) certain ART regimens might produce CNS side effects that manifest themselves as hearing difficulties, and/or (3) some ART regimens may treat CNS HIV inadequately, perhaps due to insufficient CNS drug levels, which is reflected as a central hearing deficit. Monitoring of central hearing parameters could be used to track central effects of either HIV or ART.
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http://dx.doi.org/10.1097/01.aud.0000439101.07257.edDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3999286PMC
February 2015

Lateralized auditory symptoms in central neuroaudiology disorder.

J Am Acad Audiol 2013 Jul-Aug;24(7):556-63

Department of Speech, Language, and Hearing Sciences, University of Connecticut.

Many individuals with central auditory nervous system (CANS) pathology/disorder report a variety of auditory symptoms with difficulty hearing in noise being one of the most common complaints (Chermak and Musiek, 1992) Interestingly, there seems to be a paucity of information in the literature on lateralized hearing loss symptoms in patients with central auditory disorders. Reported here is a case where the patient reported auditory symptoms, specifically hearing loss that was lateralized distinctly to the right ear. This ear was contralateral to a stroke that involved the left hemisphere with neural compromise limited primarily to the left Heschl's gyrus. Although the patient reported other hearing difficulties, the lateralized symptom of right-sided hearing loss seemed to be the most noticed. While the pure-tone audiogram was totally disassociated from the right ear auditory symptoms, central auditory tests revealed a marked and consistent right ear deficit, which was consistent with the site of lesion. It is rare that a relatively small lesion in Heschl's gyrus results in the perception of hearing loss so specifically localized to the right ear. It is also of interest that a patient with definite complaints of hearing loss would yield a normal, highly symmetrical pure-tone audiogram. The triad of patient symptoms, anatomy of the lesion, and central auditory test findings in this case are discussed, and theories as to possible underlying mechanisms for the patient's auditory deficits are provided.
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http://dx.doi.org/10.3766/jaaa.24.7.4DOI Listing
June 2014

Auditory processing following consecutive right temporal lobe resections: a prospective case study.

J Am Acad Audiol 2013 Jul-Aug;24(7):535-43

Department of Neurology, Johns Hopkins School of Medicine, Baltimore, MD; Department of Audiology, Speech Language Pathology and Deaf Studies, Towson University, Baltimore, MD.

Background: The role of the right temporal lobe in processing speech is not well understood. Although the left temporal lobe has long been recognized as critical for speech perception, there is growing evidence for right hemisphere involvement. To investigate whether the right temporal lobe is critical for auditory speech processing, we studied prospectively a normal-hearing patient who underwent consecutive right temporal lobe resections for treatment of medically intractable seizures.

Purpose: To test the hypothesis that the right temporal lobe is critical for auditory speech processing.

Research Design: We used a prospective, repeated-measure, single-case design. Auditory processing was evaluated using behavioral tests of speech recognition (words, sentences) under multiple listening conditions (e.g., quiet, background noise, etc.). Auditory processing of nonspeech sounds was measured by pitch pattern sequencing and environmental sound recognition tasks.

Data Collection: Repeat behavioral testing was performed at four time points over a 2 yr period: before and after consecutive right temporal lobe resection surgeries.

Results: Before surgery, the patient demonstrated normal speech recognition in quiet and under real-world listening conditions (background noise, filtered speech). After the initial right anterior temporal resection, speech recognition scores declined under adverse listening conditions, especially for the left ear, but remained largely within normal limits. Following resection of the right superior temporal gyrus 1 yr later, speech recognition in quiet and nonspeech sound processing (pitch patterns, environmental sounds) remained intact. However, speech recognition under adverse listening conditions was severely impaired.

Conclusions: The right superior temporal gyrus appears to be critical for auditory processing of speech under real-world listening conditions.
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http://dx.doi.org/10.3766/jaaa.24.7.2DOI Listing
June 2014

Endogenous dynorphins, glutamate and N-methyl-d-aspartate (NMDA) receptors may participate in a stress-mediated Type-I auditory neural exacerbation of tinnitus.

Brain Res 2013 Mar 10;1499:80-108. Epub 2013 Jan 10.

School of Health Sciences and Department of Biological, Geological and Environmental Sciences, 217 Stilwell Hall, Cleveland State University, Cleveland, OH 44115, USA.

Tinnitus is the phantom perception of sounds occurring in the absence of an external auditory stimulus. Tinnitus: [1] effects 50 million individuals, [2] often results from acoustic trauma and, [3] is very often exacerbated under stressful conditions. Tinnitus may result from lesions occurring at any location in the auditory system, but its mechanisms are poorly understood. Evidence is provided supporting an endogenous dynorphin-mediated potentiation of glutamate excitotoxicity at cochlear Type-I auditory dendrites that may well exacerbate chronic subjective neural-generated tinnitus during periods of heightened stress. The proposed mechanism is based on the following: [1] lateral efferent olivocochlear (LEOC) axon terminals contain endogenous dynorphin neuromodulators and are presynaptic to cochlear Type-I auditory dendrites that bear both κ-opioid and N-methyl-d-aspartate (NMDA) receptors/binding sites; [2] the release of presynaptic LEOC dynorphins is likely to be triggered by sympathetic stress via the locus coeruleus; [3] sodium salicylate induces an acute excitotoxicity by potentiating glutamate neurotransmitter effects at cochlear NMDA receptors, resulting in a Type-I auditory neural-generated tinnitus; [4] dynorphins participate in central NMDA-receptor-mediated excitotoxic inflammation; and [5] κ-opioid receptor ligands also modulate Type-I auditory neural activity by potentiating glutamate at cochlear NMDA receptors. A stress-activated release of dynorphins into the cochlea could potentiate the already excitotoxic effects of glutamate, producing: [1] hyperacusis, together with an acute exacerbation of [2] chronic aberrant Type-I neural activity and [3] a worsening of the activity-dependent central auditory neural plasticity changes that must certainly generate the perception of tinnitus. Treatment options are discussed.
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http://dx.doi.org/10.1016/j.brainres.2013.01.006DOI Listing
March 2013

N1-p2 recordings to gaps in broadband noise.

J Am Acad Audiol 2013 Jan;24(1):37-45

Department of Communication Sciences, University of Connecticut, Storrs, CT, USA.

Background: Normal temporal processing is important for the perception of speech in quiet and in difficult listening situations. Temporal resolution is commonly measured using a behavioral gap detection task, where the patient or subject must participate in the evaluation process. This is difficult to achieve with subjects who cannot reliably complete a behavioral test. However, recent research has investigated the use of evoked potential measures to evaluate gap detection.

Purpose: The purpose of the current study was to record N1-P2 responses to gaps in broadband noise in normal hearing young adults. Comparisons were made of the N1 and P2 latencies, amplitudes, and morphology to different length gaps in noise in an effort to quantify the changing responses of the brain to these stimuli. It was the goal of this study to show that electrophysiological recordings can be used to evaluate temporal resolution and measure the influence of short and long gaps on the N1-P2 waveform.

Research Design: This study used a repeated-measures design. All subjects completed a behavioral gap detection procedure to establish their behavioral gap detection threshold (BGDT). N1-P2 waveforms were recorded to the gap in a broadband noise. Gap durations were 20 msec, 2 msec above their BGDT, and 2 msec. These durations were chosen to represent a suprathreshold gap, a near-threshold gap, and a subthreshold gap.

Study Sample: Fifteen normal-hearing young adult females were evaluated. Subjects were recruited from the local university community.

Data Collection And Analysis: Latencies and amplitudes for N1 and P2 were compared across gap durations for all subjects using a repeated-measures analysis of variance. A qualitative description of responses was also included.

Results: Most subjects did not display an N1-P2 response to a 2 msec gap, but all subjects had present clear evoked potential responses to 20 msec and 2+ msec gaps. Decreasing gap duration toward threshold resulted in decreasing waveform amplitude. However, N1 and P2 latencies remained stable as gap duration changed.

Conclusions: N1-P2 waveforms can be elicited by gaps in noise in young normal-hearing adults. The responses are present as low as 2 msec above behavioral gap detection thresholds (BGDT). Gaps that are below BGDT do not generally evoke an electrophysiological response. These findings indicate that when a waveform is present, the gap duration is likely above their BGDT. Waveform amplitude is also a good index of gap detection, since amplitude decreases with decreasing gap duration. Future studies in this area will focus on various age groups and individuals with auditory disorders.
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http://dx.doi.org/10.3766/jaaa.24.1.5DOI Listing
January 2013

Efficacy of auditory interventions for central auditory processing disorder: a response to Fey et al. (2011).

Lang Speech Hear Serv Sch 2012 Jul;43(3):381-6

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.
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http://dx.doi.org/10.1044/0161-1461(2012/11-0085)DOI Listing
July 2012

Ear and electrode effects reduce within-group variability in middle latency response amplitude measures.

Int J Audiol 2012 May 9;51(5):405-12. Epub 2012 Mar 9.

Department of Surgery, Division of Communicative Disorders, University of Louisville, Louisville, Kentucky 40202, USA.

Objectives: To establish normative amplitude values for relative difference measurements of the middle latency response (MLR) in normal-hearing pediatrics and to determine if these measurements provided a significant reduction of within-group variability when compared to raw, absolute amplitude measures. A relative amplitude difference is defined in the present paper as the difference in Na-Pa amplitude between two electrodes (e.g. |Na-Pa at C3 minus Na-Pa at C4|, or electrode effects) or between two ears (e.g. |Na-Pa on left ear stimulation minus Na-Pa on right ear stimulation|, or ear effects). In contrast, an absolute amplitude is defined as a single Na-Pa measurement made at one electrode for stimulation of one ear (e.g. Na-Pa measured at C3 on left ear stimulation).

Design: Cross-sectional study.

Study Sample: 155 pediatrics with normal peripheral and central hearing, and no history of psychological, neurological, or learning disability issues.

Results: Within-group variability was significantly smaller for relative differences when compared to absolute amplitude measures. Electrode effects showed significantly less variability than ear effects. Normative values for ear and electrode effects were reported.

Conclusions: Relative differences may provide better utility in the clinical diagnosis of central auditory pathology in pediatrics when compared to absolute amplitude measures because these difference measures show significantly lower variability when examined across subjects.
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http://dx.doi.org/10.3109/14992027.2012.658970DOI Listing
May 2012

Patient-reported auditory functions after stroke of the central auditory pathway.

Stroke 2012 May 1;43(5):1285-9. Epub 2012 Mar 1.

Neuro-otology Department, National Hospital for Neurology and Neurosurgery, London, UK.

Background And Purpose: Auditory functional limitations experienced by patients after stroke of the central auditory pathways remain underinvestigated. Purpose- To measure patient-reported hearing difficulties in everyday life in nonaphasic patients with stroke of the auditory brain versus normal control subjects. To examine how hearing difficulties correlate with auditory tests and site of lesion in individual cases.

Methods: We recruited 21 individuals with auditory brain stroke (excluding those with aphasia) diagnosed on the basis of a brain MRI conducted 1 to 2 weeks after the stroke and assessed in the chronic stage of stroke. Twenty-three controls matched for age and hearing were also recruited. All subjects completed the Amsterdam Inventory for Auditory Disability (consisting of subscales of sound detection, recognition, localization, speech in quiet, speech in noise) and underwent baseline audiometry and central auditory processing tests (dichotic digits, frequency and duration patterns, gaps in noise).

Results: Sound recognition and localization subscores of the inventory were significantly worse in case subjects versus control subjects, with severe and significant functional limitation (z score >3) reported by 9 out of 21 case subjects. None of the inventory subscales correlated with audiometric thresholds, but localization and recognition subscales showed a moderate to strong correlation with dichotic digits (left ear) and pattern tests.

Conclusions: A substantial proportion of patients may experience and report severe auditory functional limitations not limited to speech sounds after stroke of the auditory brain. A hearing questionnaire may help identify patients who require more extensive assessment to inform rehabilitation plans.
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http://dx.doi.org/10.1161/STROKEAHA.111.644039DOI Listing
May 2012

Diagnostic accuracy of established central auditory processing test batteries in patients with documented brain lesions.

J Am Acad Audiol 2011 Jun;22(6):342-58

Neuroaudiology Laboratory, University of Connecticut, Storrs, CT 06238, USA.

Purpose: The sensitivity, specificity, and efficiency of commonly used behavioral central auditory processing tests and test batteries were determined for 20 individuals with known lesions of the central auditory nervous system (CANS) and related auditory symptoms.

Research Design: Twenty-nine individuals with no known neurological involvement served as the control group. Both groups were administered dichotic digits (DD), competing sentences (CS), frequency patterns (FP), and low-pass filtered speech (FS) tests.

Data Analysis: Diagnostic indices for individual tests and test batteries comprised of two, three, or four tests were calculated both using a lax criterion in which failure on only one test in a battery led to a positive diagnosis and using a strict criterion in which failure on all tests in the battery was necessary to trigger a positive diagnosis.

Results: The test battery providing the best balance between sensitivity and specificity varied as a function of criterion. The two-test DD-FP battery using a strict criterion demonstrated the best balance.

Conclusions: Limitations of particular tests, the advantages of larger test batteries to more broadly examine multiple auditory processes, the degree to which the present results can be generalized clinically to populations without known brain lesions, and other clinical considerations are discussed.
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http://dx.doi.org/10.3766/jaaa.22.6.4DOI Listing
June 2011

Perspectives on dichotic listening and the corpus callosum.

Brain Cogn 2011 Jul 29;76(2):225-32. Epub 2011 Apr 29.

University of Connecticut, Department of Communication Sciences, Neuroaudiology Lab, Storrs, CT, United States.

The present review summarizes historic and recent research which has investigated the role of the corpus callosum in dichotic processing within the context of audiology. Examination of performance by certain clinical groups, including split brain patients, multiple sclerosis cases, and other types of neurological lesions is included. Maturational, age related, and genetic factors are also discussed. Finally, some attention is given to recent trends in audiology research to develop improved diagnostic and rehabilitation tools for individuals with dichotic deficits potentially related to callosal dysfunction.
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http://dx.doi.org/10.1016/j.bandc.2011.03.011DOI Listing
July 2011

Central auditory mechanisms associated with cochlear implantation: an overview of selected studies and comment.

Cochlear Implants Int 2010 Jun;11 Suppl 1:15-28

Department of Communication Sciences, Neuroaudiology Lab, University of Connecticut, Storrs, CT 06269, USA.

Recently, the evaluation of the role of the central auditory system in the utilization of cochlear implants has received much attention. In order to fully understand the results of cochlear implantation, one must have an understanding of how the brain is influenced by electrical stimulation of the auditory nerve. This review provides an overview of the structure and function of the central auditory nervous system and the changes that occur as a result of cochlear implant use. Evidence of central auditory plasticity is discussed highlighting key imaging and evoked potential studies.
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http://dx.doi.org/10.1179/146701010X12671178390753DOI Listing
June 2010

GIN (Gaps-In-Noise) performance in the pediatric population.

J Am Acad Audiol 2009 Apr;20(4):229-38

Division of Otolaryngology, Department of Surgery, University of Kentucky College of Medicine, Chandler Medical Center, B317 Kentucky Clinic, Lexington, KY, 40536-0284, USA.

Background: The recently developed Gaps-In-Noise (GIN) test has provided a new diagnostic tool for the detection of temporal resolution deficits. Previous reports indicate that the GIN is a relatively sensitive tool for the diagnosis of central auditory processing disorder ([C]APD) in adult populations.

Purpose: The purpose of the present study was to determine the feasibility of the GIN test in the pediatric population.

Research Design: This was a prospective pseudorandomized investigation.

Study Sample: This investigation involved administration of the GIN to 72 participants divided into six groups of normal children ranging from 7 through 18 years of age.

Data Collection And Analysis: The approximate GIN threshold (the shortest gap duration for which at least four of six gaps were correctly identified) served as the dependent variable. Results were analyzed using an ANOVA to examine between- and within-group differences.

Results: No statistically significant differences were seen in GIN thresholds among age groups. In addition, within group analysis yielded no statistically significant differences between ears within each age group. No developmental effect was seen in GIN thresholds between the ages of 7 and 18 years. Children as young as age 7 are able to complete the GIN with no significant difficulty and perform at levels commensurate with normal adults. The absence of ear differences suggests that temporal resolution as measured by the GIN is an auditory process that develops relatively early and symmetrically (i.e., no laterality or ear dominance effects).

Conclusions: The GIN procedure appears to be a feasible measure of temporal resolution in both pediatric and adult populations.
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http://dx.doi.org/10.3766/jaaa.20.4.3DOI Listing
April 2009