Biomedical subjects

G P Widin

Publications and source records attributed to G P Widin.

4 recordsLinked to original sources

PubMed1987

Speech waveform envelope cues for consonant recognition.

This study investigated the cues for consonant recognition that are available in the time-intensity envelope of speech. Twelve normal-hearing subjects listened to three sets of spectrally identical noise stimuli created by multiplying noise with the speech envelopes of 19(aCa) natural-speech nonsense syllables. The speech envelope for each of the three noise conditions was derived using a different low-pass filter cutoff (20, 200, and 2000 Hz). Average consonant identification performance was above chance for the three noise conditions and improved significantly with the increase in envelope bandwidth from 20-200 Hz. SINDSCAL multidimensional scaling analysis of the consonant confusions data identified three speech envelope features that divided the 19 consonants into four envelope feature groups ("envemes"). The enveme groups in combination with visually distinctive speech feature groupings ("visemes") can distinguish most of the 19 consonants. These results suggest that near-perfect consonant identification performance could be attained by subjects who receive only enveme and viseme information and no spectral information.

Cochlear Implants↗

PubMed1986

Effects of forward and simultaneous masking on intensity discrimination.

Experiments on intensity discrimination determine the size of the smallest detectable increment added to a fixed pedestal. This paper examines the effects of a masker which either precedes the pedestal (forward masking) or is simultaneous with the pedestal. The increment and pedestal were 1-kHz tones masked in forward masking by pure tones and in simultaneous masking by a broadband noise. Simultaneous masking by the broadband noise eliminates the "near miss" to Weber's law, and thus degrades intensity discrimination at high pedestal levels. Forward masking by the pure tone also degrades intensity discrimination, which may, in part, be explained by the elimination of the near miss. However, the effect on intensity discrimination in some cases is greater in forward than in simultaneous masking, suggesting that some additional process (e.g., adaptation) is involved.

Adult↗

PubMed1984

Interaction of spontaneous oto-acoustic emissions and external sounds.

Spontaneous oto-acoustic emissions (SOAEs) were detected in eight of 19 ears from 12 persons with normal hearing. On a subset of these individuals, additional characteristics of SOAEs were studied including the suppression of SOAE level caused by an external tone. For suppressor tones below and slightly above the frequency of an SOAE, suppression is quite abrupt (about 5 dB of SOAE level reduction per dB increase in suppressor level); however, as suppressor frequency increases above the SOAE, the rate of suppression decreases. A release from suppression was demonstrated by the interaction of an SOAE with two external tones. When a tone above the SOAE frequency causes suppression, a second tone above the suppressor frequency can cause the SOAE to increase nearly to its ambient level. This finding is interpreted as the second tone having suppressed some aspect of the intracochlear influence of the first tone. The growth rate of this secondary suppression appears to be near 1 dB/dB, a value similar to rates derived from existing measures of two-tone suppression observed in auditory-nerve-fiber recordings in laboratory mammals.

Acoustic Stimulation↗

PubMed1980

Masker interaction in pure-tone forward masking.

Forward masking of a 1-kHZ, 20-ms probe was examined using two temporally distinct 1-kHZ, 20-ms maskers, separated by 6.5 ms. The interval between the second masker and the probe was the same as the interval between the first and second masker. Masking functions were obtained for each masker separately, and for varying levels of one masker with a fixed level of the other. The presence of the first masker at a fixed level raised the probe threshold over that obtained with the second masker alone: this elevation was approximately constant, independent of the level of the second masker. The results indicate that masking effects of the two maskers are not independent, i.e., the maskers interact. Several models of masker interaction are discussed.

Humans↗