Auditory Processing Dysfunction Research Articles

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

Military risk factors such as blast exposure, noise exposure, head trauma, and neurotoxin exposure place Service members and Veterans at risk for deficits associated with auditory processing dysfunction. However, there is no clinical guidance specific to the treatment of auditory processing deficits in this unique population. We provide an overview of available treatments and their limited supporting evidence for use in adults, emphasizing the need for multidisciplinary case management and interdisciplinary research to support evidence-based solutions. We explored relevant literature to inform the treatment of auditory processing dysfunction in adults, with emphasis on findings involving active or former military personnel. We were able to identify a limited number of studies, pertaining primarily to the treatment of auditory processing deficits through the use of assistive technologies and training strategies. We assessed the current state of the science for knowledge gaps that warrant additional study. Auditory processing deficits often co-occur with other military injuries and may pose significant risk in military operational and occupational settings. Research is needed to advance clinical diagnostic and rehabilitative capabilities, guide treatment planning, support effective multidisciplinary management, and inform fitness-for-duty standards. We emphasize the need for an inclusive approach to the assessment and treatment of auditory processing concerns in Service members and Veterans and for evidence-based solutions to address complex military risk factors and injuries.

Prognostic Value of a Test of Central Auditory Function in Conversion from Mild Cognitive Impairment to Dementia

Background/Objective: It has been suggested that central auditory processing dysfunction might precede the development of cognitive decline and Alzheimer’s disease (AD). The Dichotic Digits Test (DDT) has been proposed as a test of central auditory function. Our objective was to evaluate the predictive capacity of the DDT in conversion from mild cognitive impairment (MCI) to dementia. Methods: A total of 57 participants (26 females) with MCI were tested at baseline with pure tone audiometry, speech in quiet and in noise, and the DDT. The cognitive outcome was retrieved from medical files after 5 years. Groupwise comparisons of the baseline DDT scores were performed and the relative risk was calculated. Results: Altogether 22 subjects developed any kind of dementia. Of the original 57 individuals within the MCI group, 15 developed AD and 7 developed other types of dementia. There was no significant difference in baseline DDT scores between the participants who converted to AD and those who did not. However, the group who developed other types of dementia (especially frontotemporal dementia) had lower DDT scores in the left ear than those participants who did not develop dementia. With a baseline DDT score below 50% correct responses, the participants diagnosed with MCI had a 2.49-times-higher risk of developing dementia than those with scores of 50% or better. Conclusion: The DDT as a central auditory test may be suitable when evaluating cognitive decline.

The Effect of Aging and the High-Frequency Auditory Threshold on Speech-Evoked Mismatch Negativity in a Noisy Background

Mismatch negativity (MMN) has been widely used to study the function of central auditory processing in the elderly. However, current research has not yet considered the effect of noise and high-frequency hearing threshold on MMN in the elderly. The aim of this study was to evaluate the effect of aging and high-frequency hearing loss on speech-related MMN in noisy backgrounds. Additionally, the possible mechanisms of central auditory processing dysfunction in the elderly were investigated. Fifty people aged 61-80 (70 ± 5.8) years were recruited for this study. They were divided into a 61- to 70-year-old group and a 71- to 80-year-old group. Fifty younger adults aged 21-40 (31 ± 5.3) years were recruited as healthy controls. Pure-tone hearing thresholds were recorded. A speech discrimination score (SDS) and a speech-evoked MMN under white noise with a bandwidth from 125 to 8,000 Hz background condition were recorded. The relationships between SDS and MMN latency and amplitude were analyzed. The effects of age and binaural 2,000-, 4,000- and 8,000-Hz pure-tone hearing thresholds on MMN latency and amplitude were analyzed. We found that the hearing thresholds of 2,000, 4,000 and 8,000 Hz in the 61- to 70-year-old and 71- to 80-year-old groups were higher than those in the control group. The SDS in a noisy background in the 61- to 70-year-old and 71- to 80-year-old groups were lower than those in the control group. Speech-evoked MMN latency was longer in the 61- to 70-year-old and in the 71- to 80-year-old groups than in the control group (215.8 ± 14.2 ms). SDS and speech-evoked MMN latency were negatively correlated. Age and speech-evoked MMN latency were positively correlated, as were the binaural 4,000- to 8,000-Hz pure-tone hearing thresholds and speech-evoked MMN. This study suggests that in elderly subjects, the function of preattentive central auditory processing changes. Additionally, increasing age and high-frequency hearing thresholds create a synergy in neurons that is weakened in the MMN time window, which may be a cause of central auditory processing disorders in elderly subjects in noisy background conditions.

Effects of noise exposure in combination with exposures to JP-8 jet fuel

The objective was to evaluate the potency of JP-8 jet fuel to enhance noise-induced hearing loss using inhalation exposure to fuel and simultaneous exposure to noise with male & female Fischer 344 (F344) rats for 6 h/d, 5 d/wk for 4 wk (200, 750, or 1500 mg/m3). Parallel groups of rats also received nondamaging noise (85 dB) in combination with fuel, noise alone (75, 85, or 95 dB), or no exposure to fuel or noise. Computer software was used to generate a pure and precisely filtered white noise file of one octave band, centered at 8 kHz. The filtered file was then played through electrodynamic shakers that induced vibration from the outside in the metal plenum at the bottom of each exposure chamber to produce noise. Significant concentration-related impairment of auditory function measured by distortion product otoacoustic emissions (DPOAE) and compound action potential (CAP) threshold was seen in rats exposed to combined JP-8 (1500 mg/m3) plus noise (85 dB) with trends toward impairment at 750 mg/m3 JP-8 plus noise (85 dB). JP-8 alone exerted no effect on auditory function. Noise was able to disrupt DPOAE and increase auditory thresholds when noise exposure was at 95 dB. Two additional studies with JP-8 (1000 mg/m3) and noise (85 dB), one with F344 rats and one with Long Evans rats did not affect auditory function. However, a pilot assessment indicated a central auditory processing dysfunction (i.e., impaired brainstem encoding of stimulus intensity) among F344 and LE rats exposed to JP-8 alone and JP-8 with noise.

Quantifying supra-threshold sensory deficits in listeners with normal hearing thresholds

There is growing suspicion that some listeners with normal-hearing thresholds may be suffering from a specific form of sensory deficit—a loss of afferent auditory nerve fibers. We believe such deficits manifest behaviorally in conditions where perception depends upon precise spectro-temporal coding of supra-threshold sound. In our lab, we find striking inter-subject differences in perceptual ability even among listeners with normal hearing thresholds who have no complaints of hearing difficulty and have never sought clinical intervention. Among such ordinary listeners, those who perform relatively poorly on selective attention tasks (requiring the listener to focus on one sound stream presented amidst competing sound streams) also exhibit relatively weak temporal coding in subcortical responses and have poor thresholds for detecting fine temporal cues in supra-threshold sound. Here, we review the evidence for supra-threshold hearing deficits and describe measures that reveal this sensory loss. Given our findings in ordinary adult listeners, it stands to reason that at least a portion of the listeners who are diagnosed with central auditory processing dysfunction may suffer from similar sensory deficits, explaining why they have trouble communicating in many everyday social settings.

Auditory verbal hallucinations in schizophrenia correlate with P50 gating

ObjectiveWhile auditory verbal hallucinations (AVHs) are a common symptom of schizophrenia, the underlying mechanisms behind these perceptual anomalies and their effects on auditory processing are not fully understood. Patients suffering from schizophrenia have been shown to exhibit impaired sensory gating of acoustic stimuli, evidenced by a failure to inhibit the auditory P50 scalp recorded middle latency evoked potential response to the second of two paired auditory “clicks” (S1–S2). MethodsBecause abnormal activation of auditory pathways is associated with a general AVH trait of schizophrenia patients, this study correlated the hallucinatory trait subscale of the Psychotic Symptoms Ratings Scale (PSYRATS) scores of 16 actively hallucinating patients with their P50 responses to S1 and S2 as well as sensory gating indices. P50 gating in patients was also compared to twenty one healthy controls. ResultsControl S1 amplitudes were significantly greater than those of patients. There was a negative correlation between PSYRATS scores and gating difference score as well as with S1 amplitude, and a positive correlation with gating ratio, indicating the global trait of hallucinating schizophrenia patients may be associated with deficiencies in the processing of auditory stimuli. No significant correlation was found when the same analysis was applied to a state-dependent hallucination ratings scale. SignificanceResults suggest the relationship between auditory hallucinations and auditory processing dysfunction measured by P50 response is more trait than state dependent in schizophrenia.

Case Study of Central Auditory Processing in Patients with Stroke

This study aimed to investigate central auditory processing dysfunction in patients with stroke. Three patients who had suffered strokes with confirmed auditory pathway involvement, participated. All subjects had normal hearing bilaterally, and were right-handed. All subjects completed K-MMSE (Korean version of Mini-Mental State Exam) and K-WAB (Korean version-the Western Aphasia Battery), and performed Korean Central Auditory Processing Assessment (CAPA-K) battery, including Frequency Pattern test, Dichotic Digit test, Filtered Word test, Compressed Speech test, Speech in Noise test, and Binaural Fusion test. The scores for the each test were evaluated by comparing the normative data in young adult population for the standardization of CAPA-K battery. The results of the study revealed that all three subjects had difficulties in central auditory processing. S1 (male, 17 years, Rt. middle cerebral artery infarction including Rt. insula and basal ganglia) showed poor performance in contralateral ear to the lesion in all speech recognition tests. Contralateral ear suppression was also seen in dichotic testing. Furthermore, frequency pattern recognition was poorer in the linguistic labeling condition than in the humming condition in both ears. S2 (female, 46 years, both pontine infarction including lateral lemniscus and superior olivary complex) demonstrated difficulties through the entire tests whereas S3 (male, 51 years, Lt. pontine infarction including lateral lemniscus) showed normal performance in speech recognition test and monaural-low redundancy speech tests in both ears. Regardless of side of lesion, temporal processing difficulties in both ears were found in patients associated with pontine infarction. In these cases, auditory dysfunction resulting from stroke varied with the location and extent of auditory pathway infarction. Therefore, more cases are needed to identify the central auditory dysfunction in patients with stroke.

Clinical evaluation of central auditory processing functions in the elderly

EnAbstract Background Central auditory processing dysfunction is a general term that is applied to individuals whose hearing in quiet settings is normal or almost normal, and yet who have substantial hearing difficulty in the presence of auditory stressors such as competing noise and other difficult hearing situations. It is noticed that the prevalence of central auditory processing dysfunction increases with age. Objectives Evaluation of the effects of aging on central auditory processing in elderly individuals who report good hearing sensitivity. Methodology Thirty elderly individuals ranging in age from 60 to 75 years, right-handed, and who reported good hearing sensitivity participated in this study. The results of the synthetic sentence identification with an ipsilateral competitive message (SSI–ICM) and staggered spondee words (SSW) tests were compared with those of 15 young adults ranging in age from 20 to 40 years with normal hearing sensitivity as a control group. Results The findings of the study showed a statistically significant difference between the control group and the elderly group in terms of SSI, with a lower percentage in the elderly group. The results of the SSW test showed that there was a significant difference in scoring between competing and noncompeting conditions, with more affection in the competing condition in both the control and the elderly groups. When we compared the control group and the elderly group in terms of the SSW error score in the competing condition in both ears, it was found that there was a statistically significant difference between the two groups, with more error scores in the elderly group. Conclusion Central auditory processing is affected by aging as shown by the lower percentage of results of the SSI–ICM test and more errors in the SSW test mainly in the competing conditions relative to the control group.

Poster #199 EFFECT OF MEDICATION IN COGNITION AND INSIGHT IN PSYCHOTIC PATIENTS

While auditory verbal hallucinations (AVHs) are a common symptom of schizophrenia, the underlying mechanisms behind these perceptual anomalies and their effects on auditory processing are not fully understood. Patients suffering from schizophrenia have been shown to exhibit impaired sensory gating of acoustic stimuli, evidenced by a failure to inhibit the auditory P50 scalp recorded middle latency evoked potential response to the second of two paired auditory “clicks” (S1–S2).Because abnormal activation of auditory pathways is associated with a general AVH trait of schizophrenia patients, this study correlated the hallucinatory trait subscale of the Psychotic Symptoms Ratings Scale (PSYRATS) scores of 16 actively hallucinating patients with their P50 responses to S1 and S2 as well as sensory gating indices. P50 gating in patients was also compared to twenty one healthy controls.Control S1 amplitudes were significantly greater than those of patients. There was a negative correlation between PSYRATS scores and gating difference score as well as with S1 amplitude, and a positive correlation with gating ratio, indicating the global trait of hallucinating schizophrenia patients may be associated with deficiencies in the processing of auditory stimuli. No significant correlation was found when the same analysis was applied to a state-dependent hallucination ratings scale.Results suggest the relationship between auditory hallucinations and auditory processing dysfunction measured by P50 response is more trait than state dependent in schizophrenia.

Central auditory function in early Alzheimer's disease and in mild cognitive impairment

to investigate auditory function in subjects with early Alzheimer's disease, mild cognitive impairment and with subjective memory complaints, in search of signs of central auditory processing dysfunction even in early stages of cognitive impairment. a consecutive group of men and women, referred to the Memory Clinic at the Karolinska University Hospital, was approached for inclusion in this prospective study. One hundred and thirty-six subjects, mean age 64 years (range 50-78 years), diagnosed with Alzheimer's disease (n = 43), mild cognitive impairment (n = 59) or with subjective memory complaints (n = 34), were included. auditory function was assessed with pure tone audiometry, speech perception in quiet and in background noise and dichotic digits tests with two or three digits. pure tone audiometry and speech perception scores in quiet and in background noise were normal for age and without between-group differences. Dichotic digits tests showed strongly significant differences between the three groups, where the Alzheimer's disease group performed significantly poorer than the other two groups, with the mild cognitive impairment group in an intermediate position. our results demonstrate that central auditory processing dysfunction is highly evident in subjects with Alzheimer's disease, and to a considerable extent even in subjects with mild cognitive impairment.

Executive Dysfunction and Presbycusis in Older Persons With and Without Memory Loss and Dementia

To determine the relation of age-related auditory processing dysfunction and executive functioning. Central auditory dysfunction is common in Alzheimer dementia, but the mechanism is not established. A total of 313 volunteers from the Adult Changes in Thought surveillance cohort with adequate peripheral hearing were included in the study. Outcome measures such as (1) peripheral audition; (2) auditory-evoked potentials; (3) central auditory tests (Synthetic Sentence Identification with Ipsilateral Competing Message, Dichotic Sentence Identification, Dichotic Digits); (4) Executive Functioning: Trail Making; Clock Drawing, Stroop Color and Word, and subtests from the Cognitive Abilities Screening Instrument were used to measuring the mental concentration. A composite executive functioning score was created using item response theory. The composite executive functioning score was significantly associated with each central auditory measure, explaining 8% to 21% of the variance. Trails B test was most strongly associated with the auditory outcomes, explaining 8% to 14% of the variance. The relation between executive functioning and central auditory function was still significant when participants diagnosed with memory impairment or dementia were excluded. In elderly persons, reduced executive functioning is associated with central auditory processing, but not with primary auditory function. This suggests that central presbycusis and executive dysfunction may result from similar neurodegenerative processes.

Central auditory processing in aging: the dichotic listening paradigm.

Aging is associated with cognitive changing. Central auditory processing dysfunction may explain some understanding difficulties in elderly. It may be evaluated with the dichotic listening (DL) test, a widely-used experimental paradigm for studying inter-hemispheric interactions and attentional processes. This study examines central auditory language processing with a dichotic listening task in right-handed old subjects according to their age. Cross sectional-study. memory clinic and geriatric unit. Adult group (Ad) consisted in 26 subjects (21 women and 5 men) aged 50-69 years and an old adults group (Old-Ad) consisted in 20 subjects (19 women and 1 man) aged 70 to 89 years. DL consisted in a free-recall word task and a digit forced-attention task (forced-right: FR and forced-left: FL) in order to study central auditory language processing. In addition, we used neuropsychological tests to study executive functions and cognitive control, sustained by the prefrontal cortex. In the free recall condition, we confirmed the classic right ear advantage (REA) in both groups, particularly in older subjects. In the forced condition, we observed an ear advantage with a change in ear asymmetry as a consequence of instruction: REA in FR and a left-ear advantage (LEA) in FL. We compared contaminations by the contra-lateral inattentive ear: reports of the left ear (LE) in the FR condition and reports of the right ear (RE) in the FL condition. Contaminations by the RE in the FL condition were more pronounced in Old-Ad suggesting difficulties in competition between the natural tendency for the RE and the instruction. In the Old-Ad group, the correlation between the RE score in FL and TMT B-A/A suggests an impairment in mental flexibility. DL may be helpful to study central auditory dysfunction in aging. Our results suggest difficulties in attentional control and executive functions. Central auditory dysfunction should be evaluated in elderly because it potentially contributes to difficulty of hearing in noisy environment with consequences in the rehabilitation of presbyacousic subjects. More studies are needed to investigate the predictive value of DL as a marker of cognitive decline, particularly executive functions.

Staggered spondaic word test in epileptic patients.

Auditory processing during childhood may be altered if there is any predisposing factor during the course of development. Neurological disorders are among the risk factors for auditory processing impairment. From this perspective, epileptic children present such a risk factor and could present auditory processing dysfunction. To evaluate central auditory processing in epileptic patients using the Staggered Spondaic Word Test (SSW) in order to verify whether these patients presented auditory disorders and whether the type of crisis partial or generalized played a role in the occurrence and type of disorder. Tertiary care hospital. Thirty-eight children and adolescents, ranging from 7 to 16 years old, with a diagnosis of epilepsy divided into two groups: 23 patients with partial crisis and 15 patients with generalized crisis. Performance in the Staggered Spondaic Word Test versus epileptic crisis type (partial or generalized). The majority of epileptic patients showed central auditory processing disorders. There were no differences in relation to crisis type. Both groups showed similar performance, although the results observed for these patients differ from what is obtained with normal populations. With regard to response bias, there were also no differences in performance between subjects with partial or generalized seizures. All possible disorders were found in both groups, without the prevalence of one specific disorder over the other. This study revealed a high prevalence of disorders among epileptic patients in relation to processing partially overlapped verbal sounds in a dichotic paradigm.

Year 2000 Position Statement: Principles and Guidelines for Early Hearing Detection and Intervention Programs.

Year 2000 Position Statement: Principles and Guidelines for Early Hearing Detection and Intervention Programs.

Kainic acid lesions in adult rats as a model of schizophrenia: changes in auditory information processing

Previous studies have suggested that intracerebroventricular kainic acid injections alter brain anatomy and neurochemistry in a manner similar to what is observed in schizophrenic patients. Disturbances in sensory information processing are one of the major symptoms of schizophrenia. Thus, the present experiments were designed to evaluate the hypothesis that hippocampal damage, induced by administration of kainic acid, would alter the processing of auditory stimuli in a paired-click paradigm. Adult male Sprague–Dawley rats were implanted for surface recording of auditory evoked potentials. At the time of electrode implantation, the rats also received bilateral injections of either kainic acid or the vehicle solution. In vehicle-treated rats, the midlatency N40 component of the auditory evoked potential was diminished in amplitude by approximately 60% in response to the second of a pair of clicks delivered 0.5 s apart. By contrast, no reduction of the N40 wave evoked by the second click was observed in kainate-treated rats. Further, administration of haloperidol, a prototypical neuroleptic agent, did not improve this auditory processing dysfunction in kainate-treated animals. Loss of auditory filtering in the paired-click paradigm and a lack of response to haloperidol in this test are typically observed in schizophrenic humans. Thus, the present results demonstrate that kainate-lesioned rats possess a functional schizophrenia-like abnormality, further reinforcing the utility of this model system for studying the basic neurobiology of schizophrenia-induced sensory processing deficits.

The Neuropathology of Developmental Dysphasia: Behavioral, Morphological, and Physiological Evidence for a Pervasive Temporal Processing Disorder.

Over the past twenty years, Tallal and colleagues have directed their research toward defining the neuropathological mechanisms responsible for developmental dysphasia. We have hypothesized that higher level auditory processing dysfunction, which has previously been associated with developmental dysphasia, may result from more basic temporal processing deficits which interfere with the resolution of rapidly presented, brief duration stimuli. This temporal processing deficit interferes with adequate perception of specific verbal stimuli which require resolution of brief duration formant transitions, resulting in disordered language development. The temporal processing deficit occurs across multiple sensory modalities, and also affects rapid and sequential motor production skills. Despite relatively normal clinical neuroradiological examinations, in vivo morphological analysis, utilizing magnetic resonance imaging techniques for quantitative volumetric measurements of specific brain structures, has identified abnormalities in superior parietal, prefrontal, and temporal cortices, as well as diencephalic and caudate nuclei. Abnormalities in structures which are involved in multimodal processing and sensory motor integration is consistent with the behavioral profile of developmental dysphasia. Two alternative hypotheses regarding the neurophysiological basis of the multimodal temporal processing disorder include: dysfunction in specifc cellular systems which subserve rapid, transient processing; and abnormal gating of sensory relay by intralaminar and reticular thalamic nuclei.

Selected Issues in Screening for Central Auditory Processing Dysfunction

Selected Issues in Screening for Central Auditory Processing Dysfunction

Auditory-Visual and Temporal-Spatial Pattern Matching Performance of Two Types of Learning-Disabled Children

Normal readers, learning-disabled readers with a visual processing dysfunction, and learning-disabled readers with an auditory processing dysfunction in grades two through four were compared on the following six pattern-matching tasks: auditory-temporal to visual-spatial (At-Vs), auditory-temporal to visual-temporal (At-Vt), visual-temporal to visual spatial (Vt-Vs), auditory-temporal to auditory-temporal (At-At), visual-temporal to visual-temporal (Vt-Vt), and visual spatial to visual-spatial (Vs-Vs). The results indicated a significant difference between the normal readers and the learning-disabled readers on the At-Vs and At-Vt tasks but not on the Vt-Vs task, which was interpreted in terms of learning-disabled readers being deficient in auditory-visual integration rather than temporal-spatial integration skills. A significant effect of learning disability type was also identified on the Vt-Vt and Vs-Vs tasks but not on the At-At or Vt-Vs tasks. These results were discussed in terms of differences in memory. Implications of the results for previous and future studies were discussed as well as possible practical implications for diagnosing modality strengths and instructing learning-disabled readers.

Effects of delayed auditory feedback on children with disorders in auditory processing

A comparison was made of the effects of delayed auditory feedback (DAF) on the speech of children with known auditory processing dysfunction and on the speech of children with no such auditory problems. Eight boys with auditory deficiencies were matched for age with eight boys whose auditory abilities were normal. Subjects performed under four DAF and four synchronous feedback conditions. Tape recordings were analyzed by three judges for duration, frequency of speech disruptions, and percentage of correct words. Although the speech of both groups was significantly affected by DAF, no significant differences between the groups were observed. Those experimental subjects with poor contextual speech showed a significantly greater number of speech disruptions and a significantly smaller percentage of correct words under DAF than did those experimental subjects with better contextual speech. The two groups tended to prolong sounds in words more than they repeated of omitted sounds in words. Both groups had more omissions and prolongations during serial speech than during recitation. The control subjects showed more repetitions during recitation than during serial speech. Both groups showed a tendency toward an adaptation effect for repetitions.