A primary operation of the inner ear is the division of acoustic stimuli into the activities of separate bands, often called cochlear filters. A history of experimentation directed at measurement of these filters has shown them to be wider in listeners with cochlear impairments than in subjects with normal hearing, an important consideration in explaining diminished speech intelligibility in noise generally found with such impairment. Historically, studies of cochlear filter have concentrated on their amplitude spectra, i.e., their frequency responses, but the present program of research has joined cutting edge research on phase responses of the filters. These data will have a dual function. First, they have considerable value for our basic understanding of auditory function; secondly, in providing information about the dynamic processing of components both within and across channels, they address issues related to the lister's ability to utilize information in the intensity and frequency contours of speech. The traditional way to tailor a hearing aid for the individual was to match the gain characteristics of the aid to threshold data from the patient. However, with the advent of powerful digital techniques for modifying the processing algorithms for new aids, it will be possible to take advantage of knowledge of the phase characteristics of cochlear filters in the patient to increase the effective signal-to-noise ratios and hence the discriminability of speech signals in everyday listening. With this in mind, the experiments on phase effects in normal and abnormal cochleas will ask how temporal processing within the auditory channels enhances spectral contrast and sensitivity to change. Both normal hearing and impaired listeners will be tested using psychophysical methods as well as tests of the acoustic reflex, a tool commonly used in audiology to measure sensitivity.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
7R01DC000626-12
Application #
6090808
Study Section
Special Emphasis Panel (ZRG1-SEN (01))
Project Start
1989-04-01
Project End
2003-03-31
Budget Start
1999-07-14
Budget End
2000-03-31
Support Year
12
Fiscal Year
1999
Total Cost
Indirect Cost
Name
Henry M. Jackson Fdn for the Adv Mil/Med
Department
Type
DUNS #
City
Rockville
State
MD
Country
United States
Zip Code
20817
Mertes, Ian B; Wilbanks, Erin C; Leek, Marjorie R (2018) Olivocochlear Efferent Activity Is Associated With the Slope of the Psychometric Function of Speech Recognition in Noise. Ear Hear 39:583-593
Shearer, Daniel E; Molis, Michelle R; Bennett, Keri O et al. (2018) Auditory stream segregation of iterated rippled noises by normal-hearing and hearing-impaired listeners. J Acoust Soc Am 143:378
Mertes, Ian B; Leek, Marjorie R (2016) Concurrent measures of contralateral suppression of transient-evoked otoacoustic emissions and of auditory steady-state responses. J Acoust Soc Am 140:2027
Molis, Michelle R; Diedesch, Anna; Gallun, Frederick et al. (2013) Vowel identification by amplitude and phase contrast. J Assoc Res Otolaryngol 14:125-37
Bennett, Keri O'Connell; Billings, Curtis J; Molis, Michelle R et al. (2012) Neural encoding and perception of speech signals in informational masking. Ear Hear 33:231-8
Billings, Curtis J; Bennett, Keri O; Molis, Michelle R et al. (2011) Cortical encoding of signals in noise: effects of stimulus type and recording paradigm. Ear Hear 32:53-60
Molis, Michelle R; Leek, Marjorie R (2011) Vowel identification by listeners with hearing impairment in response to variation in formant frequencies. J Speech Lang Hear Res 54:1211-23
Lauer, Amanda M; Dooling, Robert J; Leek, Marjorie R (2009) Psychophysical evidence of damaged active processing mechanisms in Belgian Waterslager Canaries. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 195:193-202
Lauer, Amanda M; Molis, Michelle; Leek, Marjorie R (2009) Discrimination of time-reversed harmonic complexes by normal-hearing and hearing-impaired listeners. J Assoc Res Otolaryngol 10:609-19
Lauer, Amanda M; Dooling, Robert J; Leek, Marjorie R et al. (2007) Detection and discrimination of simple and complex sounds by hearing-impaired Belgian Waterslager canaries. J Acoust Soc Am 122:3615-27

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