Clinical application of distorted speech audiometry

Non-linguistic auditory speech processing

OBJECTIVES

A method for testing auditory processing of non-linguistic speech-like stimuli was developed and evaluated.

DESIGN

Monosyllabic words were temporally reversed and distorted. Stimuli were matched for spectrum and level. Listeners discriminated between distorted and undistorted stimuli.

STUDY SAMPLE

Three groups were tested. The Normal group was comprised of 12 normal-hearing participants. The Senior group was comprised of 12 seniors. The Hearing Loss group was comprised of 12 participants with thresholds of at least 35 dB HL at one or more frequencies.

RESULTS

The Senior group scored lower than the Normal group, and the Hearing Loss group scored lower than the Senior group. Scores for forward compressed speech were slightly higher than backward compressed speech but the difference was not statistically significant. Retest scores were slightly higher than scores on the first test, but the difference was not statistically significant.

CONCLUSIONS

Large differences in discrimination of distorted speech were observed among the three groups. Age and hearing loss separately affected performance. The depressed performance of the Senior group may be a result of "hidden hearing loss" that is attributed to cochlear synaptopathy. The backward-distorted speech task may be a useful non-linguistic test of speech processing that is language independent.

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.

Acquired Central Auditory Processing Disorder in Service Members and Veterans

Purpose A growing body of evidence suggests that military service members and military veterans are at risk for deficits in central auditory processing. Risk factors include exposure to blast, neurotrauma, hazardous noise, and ototoxicants. We overview these risk factors and comorbidities, address implications for clinical assessment and care of central auditory processing deficits in service members and veterans, and specify knowledge gaps that warrant research. Method We reviewed the literature to identify studies of risk factors, assessment, and care of central auditory processing deficits in service members and veterans. We also assessed the current state of the science for knowledge gaps that warrant additional study. This literature review describes key findings relating to military risk factors and clinical considerations for the assessment and care of those exposed. Conclusions Central auditory processing deficits are associated with exposure to known military risk factors. Research is needed to characterize mechanisms, sources of variance, and differential diagnosis in this population. Existing best practices do not explicitly consider confounds faced by military personnel. Assessment and rehabilitation strategies that account for these challenges are needed. Finally, investment is critical to ensure that Veterans Affairs and Department of Defense clinical staff are informed, trained, and equipped to implement effective patient care.

Appearances are deceptive? long-term cognitive and central auditory sequelae from closed head injury ¿Las apariencias engañan? Secuelas cognitivas y auditivas centrales a largo plazo después de un traumatismo cráneo-encefálico cerrado

The purpose of the present study was to examine possible signs of long-term cognitive and/or central auditory sequelae seven to eleven years after a closed head injury (CHI) of sufficient severity to cause scull fracture and/or brain contusion. Another purpose was that this investigation should be carried out in a group of recovered trauma victims with, to the individual, no known or minimal sequelae. A computer-based set of five cognitive tests and three central auditory tests were used in a group of formerly brain-injured patients who considered themselves as well recovered. Most of the participants did not report any signs of cognitive or auditory impairment. Tests of working memory capacity, verbal information processing speed, phonological processing and verbal inference-making ability were used. Auditory brain response (ABR), distorted speech audiometry (interrupted speech), and phase audiometry were used to test central auditory function. The initial severity of brain damage, i.e. status when the patient arrived at the emergency ward, was estimated with Swedish Reaction Level Scale (RLS). Cognitive shortcomings after CHI were demonstrated in a high percentage (59%, 13/22) of the cases seven to eleven years after the injury. Central auditory processing disorders (APD) were also demonstrated in a fairly high percentage (58%, 11/19) of the subjects. None of the correlations between RLS and the results on cognitive and central auditory tests reached statistical significance. However, there was a correlation between cognitive performance and the results on the central auditory tests used in this investigation. Eighty percent (8/10) of those participants with pathologies on ABR and/or phase audiometry and/or IS also failed on one or more of the cognitive tasks, compared to 44% (4/9) among those with no signs of APD. It is possible, many years after CHI, to observe cognitive shortcomings and APD in a relatively high percentage of CHI cases that are subjectively considered to be fairly well recovered. The cognitive tasks used in the study have proved to be a sensitive method to discover cognitive impairments. Long-term cognitive sequelae and APD could not be predicted from RLS scores.

Auditory function in adrenomyeloneuropathy

Auditory brainstem responses (ABR), ipsilateral and contralateral acoustic reflexes and the masking level difference for speech (MLD) were studied in 29 patients with adrenomyeloneuropathy (AMN). Abnormalities were seen for all ABR components with Waves V and III affected to the greatest degree. For male patients with AMN, the I-III, III-V and I-V interpeak latency intervals were abnormal for a majority of patients. For female patients with AMN, the I-V and III-V interpeak latency intervals were abnormal for a majority of patients with the I-III interval less affected. Contralateral acoustic reflexes were elevated or absent for approximately 50% of ears. Ipsilateral acoustic reflexes were abnormal for 25% of ears. MLDs were significantly reduced in 72% of patients. When considered in terms of the earliest ABR wave abnormality, the earlier components of the ABR (i.e., Waves III and I) were the initial components impaired for the majority of ears. Word recognition in quiet was relatively unimpaired for all subjects. Despite the presence of marked ABR abnormalities, patients with AMN denied the presence of significant difficulty hearing.