Patricia G. Stelmachowicz, Ph.D. - US grants

The objective of this contract is the evaluation of a high-frequency audiometer and transducer assembly to determine its validity and reliability for measuring hearing thresholds in humans at frequencies beyond the limits of conventional audiometry. This will be accomplished by testing for reliability and procedural considerations with normal-hearing patients and by testing drug- and noise-exposed patients to evaluate the utility of high-frequency audiometry. Additional research will be performed to define the limits of using the calibration procedure with respect to ear canal size, to assess the feasibility of measuring auditory brainstem responses to high-frequency stimuli, and to determine threshold adaptation and temporal integration by employing high-frequency sounds.

DESCRIPTION (provided by applicant): With the widespread success of universal newborn hearing screening (UNHS) programs, it is now possible to identify hearing loss at birth and initiate amplification in early infancy. The ability to identify hearing loss at birth, however, has made the gaps in our knowledge more obvious. The overall goal of the proposed studies is to gain a better understanding of the challenges faced and the unique needs of young children with sensorineural hearing loss. Aim 1 will assess the relative benefit of an extended bandwidth hearing-aid vs. a frequency-lowering scheme to improve the audibility of high-frequency speech components for children with hearing loss. It is hypothesized that the benefit derived from these two approaches will vary as a function of degree and configuration of hearing loss. Results will provide new information regarding optimum amplification strategies for individuals with varying degrees and configurations of hearing loss. Aim 2 will examine the ability of children with and without hearing loss to perceive speech in adverse listening environments. It is hypothesized that performance will be poorer for the hearing-impaired group and that fast-acting compression will degrade performance relative to slow- acting compression. Results will provide a better understanding of children's ability to perform complex listening tasks in noise and how amplification strategies support or fail to support their perceptual strategies. Aim 3 will examine the relative contribution of acoustic-phonetic, phonotactic and language- based cues to speech perception for normal-hearing and hearing-impaired children. It is hypothesized that the patterns of reliance on language-based cues (e.g., filling in unheard acoustic-phonetic details by relying on the language context) will differ between the normal-hearing and hearing-impaired children and that developmental changes in the use of these cues will occur more rapidly in the normal-hearing group. Results will increase our understanding of individual differences in the use of perceptual strategies, the extent to which these two groups rely on language-based processes in difficult listening situations, and how these divergent strategies influence speech perception.