Behavioral evidence for possible simultaneous induction of hyperacusis and tinnitus following intense sound exposure.

Many human subjects suffering from chronic tinnitus also suffer from hyperacusis, a heightened perception of loudness at moderate to intense sound levels. While numerous studies suggest that animals develop chronic tinnitus following intense noise exposure, it is not yet clear whether sound exposure also induces chronic hyperacusis-like responses in animals. We addressed this question by examining the chronic effects of intense sound exposure on the acoustic startle response (ASR) and its suppression by background noise containing brief gaps. We compared startle amplitudes in intense tone-exposed (10 kHz, 115 dB SPL, 4 h) and age-matched controls at 2-28 weeks post-exposure. While both groups showed similar startle thresholds, exposed animals showed a hyperacusis-like augmentation of ASR at high stimulus levels. Addition of background noise had little effect on ASR in controls but had a strong suppressive effect on startle in exposed animals, indicating a sensitization to background noise. When the background noise contained a gap preceding the startle stimulus, ASR was suppressed in control animals, but exposed animals showed a marked weakening of gap-induced suppression of ASR. This weakening of gap-induced startle suppression is consistent with the interpretation that the gap may have been masked by tinnitus. The associated hyper-responsiveness to startle stimuli presented alone and the sensitization to background noise suggest that hyperacusis may have also been induced. The results indicate that noise exposure leads to increases in the gain of auditory responsiveness and may offer a model of the association of hyperacusis with tinnitus.

Assessment of tinnitus: measurement of treatment outcomes.

There is a wide range of assessment techniques for tinnitus, but no consensus has developed concerning how best to measure either the presenting features of tinnitus or the effects of tinnitus treatments. Standardization of reliable and valid tinnitus measures would provide many advantages including improving the uniformity of diagnostic and screening criteria between clinics and facilitating comparison of treatment outcomes obtained at different sites. This chapter attempts to clarify issues involved in developing self-report questionnaires for the assessment of tinnitus. While the tinnitus questionnaires that are currently available provide valuable information on which to base diagnostic and screening decisions, they were not originally developed in such a way as to maximize their sensitivity to treatment-related changes in tinnitus. As a result, their construct validity for measuring treatment benefit has not received appropriate attention. In this paper, special emphasis is devoted to the use of effect sizes as an estimate of the ability of questionnaires (and their individual items) to measure changes associated with treatment. We discuss the criteria relevant to evaluating the effectiveness of a questionnaire for diagnostic purposes vs. for treatment-evaluation purposes, and we present a detailed illustration of how the various criteria have been applied in a recent questionnaire development effort.

Development of the Three-Clinic Hearing Aid Selection Profile (HASP).

The Three-Clinic Hearing Aid Selection Profile (HASP) was developed to assess a patient's beliefs about a number of basic considerations felt to be critical to the hearing aid selection (HAS) process. These characteristics are felt to be key to the acceptance of amplification and include motivation, expectations, cost of goods and services, appearance (cosmesis), attitudes about technology, physical function/limitations, communication needs, and lifestyle. The results of the first investigation suggest that we have been successful in developing a 40-item metric with adequate internal consistency reliability that assesses the aforementioned characteristics. Second, results of the administration of this tool to a large group of individuals indicated that (1) age impacted scores on the Technology, Physical Function, and Communicative Needs subscales; (2) gender impacted scores on the Motivation, Expectation, Technology, Communicative Needs, and Appearance subscales; (3) previous hearing aid use affected scores on the Motivation subscale; (4) level of education impacted scores on the Physical Function and Lifestyle subscales; and (5) self-perceived hearing handicap had an effect on Motivation and Communicative Needs subscale scores. Percentile data collected from this subject sample are presented as a benchmark against which to evaluate responses from individual patients. Case studies are presented to illustrate the potential clinical utility of this device.

Psychometric adequacy of the Tinnitus Handicap Inventory (THI) for evaluating treatment outcome.

This study assessed the test-retest reliability/repeatability and 95 percent confidence intervals (CIs) of the Tinnitus Handicap Inventory (THI) and developed categories for classifying self-perceived tinnitus handicap severity. Twenty-nine adults with tinnitus as their primary auditory complaint served as subjects. The THI was administered on two occasions (mean interval 20 days) using a paper-pencil format. Results support the contention that the THI is psychometrically robust. Specifically, the test-retest reliability/repeatability was high. Additionally, the 95 percent CI for the THI was 20-points, indicating that a 20-point or greater change had to occur from test to retest for a change to be considered statistically significant at the 5 percent confidence level. Quartiles calculated from raw scores were used to create a matrix of values representing tinnitus severity. We conclude that the THI is a brief, easily administered, and psychometrically robust measure that evaluates the impact of tinnitus on daily living.

Perceived hearing handicap of patients with unilateral or mild hearing loss.

Using the Hearing Handicap Inventory for Adults (HHIA), we assessed self-perceived hearing handicap in a sample of 63 patients having either unilaterally normal hearing or a mild hearing loss (pure tone average < or = 40 dB hearing level). Large intersubject variability in responses to the HHIA confirmed observations that reactions to minimal hearing impairment vary greatly among patients. The individual differences in responses highlight the importance of quantifying the perceived communication and psychosocial handicap, which cannot be determined from the audiogram alone. An item examination of responses to the HHIA revealed a number of emotional and social-situational problems encountered by patients with minimal hearing loss.

Long-term effects of Ménière's disease on hearing and quality of life.

OBJECTIVE: To evaluate long-term hearing results and quality of life in patients with Ménière's disease. STUDY DESIGN: Detailed audiometric evaluation and disease-specific as well as global health quality evaluation of patients with Ménière's disease. SETTING: Ambulatory evaluation was conducted in a large multispecialty clinic. PATIENTS: Ménière's disease in only one ear, were at least 1 year posttreatment, were < 65 years of age, had no neurologic or psychologic disorders, and lived within driving distance of the ambulatory clinic. MAIN OUTCOME MEASURES: Audiometry, the Hearing Handicap Inventory, Dizziness Handicap Inventory, Tinnitus Handicap Inventory, and SF-36 Health Survey. RESULTS: No statistically significant differences in long-term hearing results were detected from natural history in medically or surgically treated patients with Ménière's disease. A significant disease-specific symptom handicap was detected. The global health handicap was greater for emotional disability than for physical disability. CONCLUSIONS: Medical and surgical treatment does not significantly influence hearing results in Ménière's disease. Patients with Ménière's disease have a greater emotional disability than a physical disability.

Using naturally produced speech to elicit the mismatch negativity.

The mismatch negativity (MMN) was recorded from 10 young adults with normal hearing using naturally produced speech contrasts. Consonant-place and vowel-height contrasts were examined in consonant-vowel (CV) syllables by pairing either the consonant /t/ or /p/ with the vowel /I/ or /E/. Vowel-height was also examined as a pseudovowel; one cycle of the vowel segment of a CV was extracted and replicated over 200 msec. A total of five contrasts were examined: vowel-height following /p/, vowel-height following /t/, consonant-place preceding /E/, consonant-place preceding /I/, and pseudovowels. Significant MMN responses were elicited from all five contrasts, albeit with different amplitudes, latencies, and waveform morphology. The pseudovowel elicited the most well-defined MMN with the greatest amplitude and was found to be significantly different from the other four contrasts. Naturally produced speech stimuli appear to be viable stimuli for eliciting the MMN.

Expectations of older adults regarding the use of hearing aids.

A 48-item questionnaire was administered to 100 older adults to determine their expectations regarding hearing aid use. The sample consisted of volunteers from a variety of senior citizen organizations and ranged in age from 55 to 92 years. Only individuals who reported no prior hearing aid usage were included in the sample. Expectations for the following factors were considered: cosmetics, acoustics, communication benefits, comfort, ease of use, cost and upkeep, and attitudes toward hearing aid use. In general, the older adults in this sample appeared to have very positive expectations regarding the use of hearing aids. Eighty-seven percent apparently have medium to high expectations for hearing aid use. Since the older adult's satisfaction with amplification may be influenced by original expectations and attitudes, the information provided in this study may be useful in improving the pre-fitting counseling of older hearing-impaired adults.

Perceived benefits of amplification as a function of central auditory status in the elderly.

A measure of perceived hearing aid benefit was obtained from 24 older hearing-impaired adults who had received their hearing aids a minimum of 6 months prior to this study. Subjects were also administered a battery of tests, including comparisons of maximum scores for phonetically balanced words and the Synthetic Sentence Identification Test to identify central auditory disorder. There appears to be no relationship between perceived hearing aid benefit and central auditory function as measured in this study. Several explanations for these somewhat surprising findings are offered, as well as clinical implications regarding the use of hearing aids by older adults.

Training influences on visual consonant and sentence recognition.

Visual consonant and sentence reception were compared in three groups of 10 normal-hearing young adult subjects including a Training group that received 14 hours of videotaped analytic visual consonant recognition training with 100% feedback concerning the correctness of their responses, a Pseudotraining group that received the same treatment as the Training group with the exception that they were not given any information about whether their responses were correct or not, and a Control group. While all three groups scored significantly higher on the post-treatment visual consonant recognition test, there was no significant difference between the Training group and the Pseudotraining group in terms of improvement scores. Furthermore, none of the groups improved in their ability to recognize visually presented sentence length material. These results are discussed in terms of the development of task-specific performance skills.

Effect of upper respiratory infection on hearing in the ferret model.

In an effort to develop an adult animal model for acquired viral-induced hearing loss, three groups of mature ferrets were inoculated intranasally with respiratory viruses (influenza A/Port Chalmers, influenza B/Mass, and parainfluenza I), which have been implicated as causative agents in idiopathic sudden hearing loss (ISHL). All ferrets challenged with influenza A/Port Chalmers (A/PC) exhibited clinical signs of infection, but neither of the other two groups exhibited such signs. Conductive and/or sensorineural hearing losses were demonstrated in eight of 15 ferrets challenged with influenza A/PC and four of 10 ferrets in the group challenged with influenza B/Mass by brainstem auditory-evoked responses (BAERs) and acoustic immittance. None of the four ferrets infected with parainfluenza I demonstrated auditory dysfunction. When auditory changes were observed, nasal washes were performed, and tissues of the middle and inner ears were collected for viral assay and morphologic examination. All ferrets demonstrating auditory changes were shown to be infected by isolation of virus from nasal tissues. Virus was isolated from eustachian tube tissue in six of the eight ferrets infected with influenza A/PC, which also demonstrated altered BAERs and one of the four infected with influenza B/Mass, which also had auditory changes. Virus was isolated from the middle ear of two ferrets infected with influenza A/PC and from the inner ear of another two ferrets from the same group. These data suggest that influenza A/PC has a greater effect on auditory function in the ferret model than either influenza B/Mass or parainfluenza I and that the ferret may be an appropriate adult model to examine the etiologic role of viral upper respiratory tract infections in some acquired hearing impairments.

Threshold prediction from the auditory 40-Hz evoked potential.

This is an investigation of the accuracy with which the 40-Hz evoked potential (EP) threshold can be used to predict low frequency behavioral audiometric thresholds. The EP thresholds for 500 and 1000 Hz tone bursts were compared with behavioral thresholds obtained from 40 hearing-impaired ears. Correlation coefficients (between EP and behavioral thresholds) of 0.79 and 0.87 were obtained for the 500 and 1000 Hz signals, respectively. Confidence intervals for EP estimates of behavioral thresholds were -10 to +30 dB for 500 Hz signals and -20 to +20 for 1000 Hz. Problems associated with the use of the EP for predicting behavioral thresholds are discussed.