W. Ward Clark

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Behavioral studies of hearing loss produced by exposure to ototraumatic agents in experimental animals, combined with the anatomical evaluation of end-organ pathology, have provided useful information about the relation between dysfunction and pathology. However, in order to attribute a given hearing loss to some pattern of cochlear damage, it is necessary(More)
  • W W Clark
  • 1991
It is well known that excessive exposure to noise results in temporary and/or permanent changes in hearing sensitivity in both human and animal subjects. The purpose of this review is to describe the major findings from laboratory studies of experimentally induced hearing losses, both temporary and permanent, resulting from exposure to noise in animal(More)
Two cases of spontaneous otoacoustic emissions (SOAEs) have been found among a sample of 28 chinchilla ears after noise exposure, and no cases of SOAEs have been found among 28 unexposed ears. Further observations of the characteristics of SOAEs recorded in the ear canals of two chinchillas after noise exposure are described. These signals were tonal,(More)
Thresholds for detection of frequency modulation were obtained from three chinchillas at seven frequencies between 320 Hz and 12.75 kHz and at three sensation levels (20, 40, 60, dB SL). These were compared with human thresholds at 40 dB SL obtained under the same conditions. Our data show no significant impact of sensation level and confirm Nelson and(More)
Experiments were performed to replicate and extend previous findings of similar categorization of voiced/voiceless consonant-vowel (CV) syllables by humans and chinchillas. A reward paradigm was applied to the question of how stimulus range affects the voice-onset-time (VOT) corresponding to the voiced/voiceless category boundary. Each of four adult(More)
Acoustic intermodulation distortion products were measured in 15 ear canals of chinchillas with normal or damaged ears. Pretreatment results showed that when two primary tones at frequencies f1 and f2, f1 less than f2, were presented at levels from 30 to 90 dB SPL, acoustic distortion products at 2f1-f2 and 2f2-f1 were 30 to 50 dB below primary-tone levels.(More)
In humans, noise exposures produce permanent hearing losses which usually begin at 4 kHz. In chinchillas, a similar pattern of hearing loss was observed following exposure for 9 or 18 days to an octave band of noise with a center frequency of 0.5 kHz. Histopathological observations of cellular degeneration showed that this exposure produced different types(More)
Changes in hearing sensitivity and cochlear damage were determined in two groups of chinchillas exposed to an octave band of noise (OBN) centered at 0.5 kHz, 95 dB SPL on two different schedules: 6 h per day for 36 days, or 15 min/h for 144 days. Hearing sensitivity was measured behaviorally at 1/4-oct frequency intervals from 0.125 to 16.0 kHz before,(More)
Clients entering a therapeutic community (TC)-oriented drug treatment program were randomly assigned to day or residential conditions and interviewed at 2 weeks and 6 months after admission. Outcomes included Addiction Severity Index composite scores and summary scores for the Beck Depression Inventory, Symptom Checklist-90-R, and a social support scale.(More)