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Literature and ideas are reviewed concerning the modulation of presbycusis - the influence of variables that can alter the severity and/or time course of presbycusis or counteract its negative aspects. Eleven topics are identified: variables related to biological aging; genetics; noise-induced hearing loss; moderately augmented acoustic environment; neural plasticity and the central auditory system; neural plasticity and hearing aids; socioeconomic and cultural barriers to hearing aid use; lifestyle (diet, exercise, etc.); medical variables; pharmaceutical interventions for presbycusis, and cognitive variables. It is concluded that the field of otogerontology will best be served by a comprehensive, integrative interaction among basic researchers and clinical scientists who will continue to learn how the auditory problems associated with presbycusis can be intentionally modulated in beneficial ways.

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The value associated with self-perceived hearing aid benefit was assessed using a "willingness-to-pay" (WTP) approach. Abbreviated Profile of Hearing Aid Benefit (APHAB) data were obtained from 79 veterans who also indicated how much they were willing to pay for each hearing aid. The results of a multiple regression analysis revealed that veterans were willing to pay $22.06 more for a hearing aid for each 1-point increase in APHAB global benefit. A second multiple regression analysis revealed that the APHAB subscale scores for Ease of Communication (EC) benefit and understanding speech in Background Noise (BN) benefit, as well as income level, were all significant predictors of WTP. In addition, each 1-point increase in EC, BN, and Reverberation benefit increased the value associated with amplification by $16.32, $16.88, and $13.78, respectively. Each 1-point increase in the Aversiveness of Sounds subscale decreased the value associated with amplification by $7.63. The mean WTP across all income groups was $981.71 per hearing aid. These data are interpreted to support the use of WTP as a valid measure of hearing aid benefit.

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Normative data, as a function of age, were obtained on a test designed to assess sensory-level speech perception capacity, the Three-Interval Forced-Choice Test of Speech Pattern Contrast Perception, otherwise known as THRIFTSPAC (or THRIFT for short). Performance under the input modalities of hearing alone, speech-reading alone, and the two combined was measured in 44 normally developing children between the ages of 5 years 7 months and 10 years 9 months. Results revealed that within each condition there were significant influences of age on performance for children below age 7 years. These changes appeared to be related to cognitive and, possibly, to phonological development. Implications for the clinical implementation of THRIFT are discussed.

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The effects of acoustic/linguistic complexity of training stimuli (i.e., isolated words vs. words in sentences) on speech perception performance was measured in 17 young children (four-to-eight years old) with severe-to-profound sensorineural hearing losses. Phase I of the study involved training on isolated words (n = 9), while Phase II involved training on words in sentences (n = 8). A four-week period of experimental training was counterbalanced with a four-week period of traditional speech-language therapy across participants and Phases. Pre- and post-treatment testing was conducted for both words in isolation and in sentences at the end of each period. Significant improvements were found as a result of experimental training in both phases. Evidence of transfer of learning was greater when sentence level stimuli (Phase II) rather than isolated word stimuli were used (Phase I). Clinical implications are discussed.

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OBJECTIVES: To determine the prevalence and characteristics of hearing loss in patients undergoing examination because of a memory disorder, to determine whether currently used screening tools were adequate for use in this specific population, and to determine if patients with Alzheimer disease reliably report hearing problems. DESIGN: Case-control study. PATIENTS: A consecutive sample of 52 patients: 30 patients who met the National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria for probable Alzheimer disease (group 1) and 22 patients with other forms of cognitive impairment (group 2). METHODS: Patients underwent a hearing screening that included a case history, a visual inspection of the external ear canal and tympanic membrane, and pure tone audiometry. Patients and their caregivers completed a questionnaire intended to assess hearing impairment and perceived disability. OUTCOME MEASURES: Pass or fail on pure tone audiometry and pass or fail on a hearing impairment questionnaire. RESULTS: Of the 52 patients, 49 had significant hearing loss. No difference was found in the failure rate between patients in groups 1 and 2. In group 1, a significant discrepancy was found between the patient's self-report and that of their caregivers, whereas in group 2, the self-report was reliable. The prevalence of hearing loss in this population greatly exceeds the prevalence in healthy aged controls. CONCLUSION: The extraordinarily high prevalence of hearing loss in this selected population suggests that a hearing evaluation should be part of any assessment of cognitive function.

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The purpose of this study was to determine whether participation in a counseling-based aural rehabilitation program would result in greater reduction of self-perceived hearing handicap than hearing aid use alone. Thirty-one postlingually hearing-impaired adults were placed into three groups after audiological evaluation. The first group received hearing aids and participated in a counseling-based aural rehabilitation (AR) program. The second group received hearing aids only. The third group received neither hearing aids nor counseling-based AR. The Hearing Handicap Inventory for the Elderly was administered to all subjects before audiological evaluation and again to all subjects 2 mo after receipt of hearing aids for the experimental groups. For both experimental groups, self-perception of hearing handicap was significantly reduced as a function of intervention when measured on any of the three Hearing Handicap Inventory for the Elderly scales, whereas there was no change in self-perception of hearing handicap for the control group on any scale. In addition, there was weak but significant evidence that participating in the counseling-based AR program in addition to hearing aid use resulted in a greater reduction of self-perceived hearing handicap than did hearing aid use alone.

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Recognition of words in sentences of known topic was measured in normally hearing adults via speechreading alone and speechreading supplemented with auditory presentation of signals intended to convey variations of voice fundamental frequency (Fo) over time. Three signals were used: (a) the low-pass filtered output of an electroglottograph (unprocessed Fo), (b) a constant amplitude sine wave whose instantaneous frequency was intended to equal that of Fo (processed Fo), and (c) the same sine wave restricted to a small number of discrete frequency steps (quantized Fo). As the number of steps in the quantized Fo contours increased from 1 to 12, the speechreading enhancement effect increased. The quantized Fo contour with 12 steps was as effective as the processed Fo contour (without quantization), but this processed contour was significantly less effective than the unprocessed electroglottograph signal. The results show that the auditory Fo speechreading enhancement effect is sensitive to the errors introduced by the Fo extraction and regeneration process used in this study. It is also sensitive to the quantization of Fo contours into less than 12 steps. Whether more than 12 steps are required for the full enhancement effect remains to be determined.

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Recognition of words in conversational sentences of known topic was measured in nine normally hearing subjects by speechreading alone and by speechreading supplemented with auditory presentation of the output of an electroglottograph. Mean word recognition probability rose from 30% to 77% with the addition of the acoustic signal. When this signal was filtered to remove possible high-frequency spectral cues, the supplemented score fell, but only by a marginally significant 7 percentage points, supporting the conclusion that voice fundamental frequency was the principal source of enhancement. Enhancement occurred for all subjects, regardless of speechreading competence.

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The perception of initial consonant voicing, final consonant voicing, pitch change, and word stress, was measured in six normal subjects, by speechreading alone, by tactile transmission of fundamental voice frequency alone, and by the two in combination. Two tactile displays were used: a single-channel (temporal) display and a 16-channel (spatial) display. By speechreading alone, all contrasts except initial consonant voicing were partially perceptible. By both tactile aids alone, all four contrasts were partially perceptable. The addition of tactile input to speechreading provided better performance than that obtained by speechreading alone. The multichannel display was found to be significantly more effective than the single-channel for perception of pitch rise/fall only.

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In two experiments, the perception of words in sentences was measured by speechreading with and without tactile presentation of voice fundamental frequency (F0). The first experiment involved normally hearing subjects and two kinds of tactile display of F0: (1) a spatial, multichannel display; and (2) a temporal, single-channel display. Mean performance with the tactile displays was found to be slightly, but significantly, better than speechreading alone, but no significant difference was found between the two displays. The second experiment involved hearing-impaired subjects and only the spatial, multi-channel display of F0. For all three subjects, after extended training, speechreading performance was significantly better with the addition of the tactile display than by speechreading alone. The improvement amounted to reductions of word recognition error of 24, 33, and 50% in the three subjects.

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Two tactile coding schemes of voice fundamental frequency were compared in terms of the detection of terminal frequency changes in simple syllable-like frequency contours. The coding schemes were: (1) temporal, single-channel--in which input frequency is represented as rate of vibration; and, (2) spatial, multichannel--in which input frequency is represented as location of vibration. An adaptive, three-interval, forced choice oddity procedure was used. The temporal, single-channel coding scheme provided a frequency resolution between 0.2 and 0.3 octaves at the fingertip. The spatial, multichannel scheme provided a spatial resolution, on the forearm, of 1-channel, which, for this 16-channel display, translates into a frequency resolution of 0.14 octaves. More learning was required with the temporal, single-channel coding scheme, than with the spatial, multichannel scheme.

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An adult with a severe, postlingually-acquired, sensorineural, hearing loss was given 2 hours a week of training in the perception of connected discourse by lipreading, supplemented by voice fundamental frequency (Fo), encoded as locus of vibratory stimulation of the forearm. Three, 3-week blocks of training in the supplemented condition were interspersed with 1-week periods of training by lipreading alone. Training was conducted via a computer-controlled, interactive video system, using a semi-automated connected discourse tracking procedure. Performance was measured as the percentage of words correctly recognized on the first presentation of new sentence material. Scores by lipreading alone averaged approximately 65 percent and remained essentially constant over the 13 weeks of training. Scores under the supplemented condition rose from 65 percent at the beginning of the study to 85 percent at the end. The final supplemented score represented roughly a 50 percent reduction of error rate, when compared with lipreading alone. Performance with the tactile supplement was not as good as with auditorily presented Fo, but was better than has previously been reported in the literature. These data provide evidence to support the notion that subjects can learn to integrate novel tactile codes with the visual stimulus during the lipreading of connected speech.

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