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Journal of the Acoustical Society of America

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May 2004

Volume 115, Issue 5, pp. 1851-2634

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Peripheral compression as a function of stimulus level and frequency region in normal-hearing listeners (P)

David A. Nelson and Anna C. Schroder

J. Acoust. Soc. Am. Volume 115, Issue 5, pp. 2221-2233 (2004); (13 pages) | Cited 14 times

Online Publication Date: 16 Apr 2004

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Fixed-probe-level temporal masking curves (TMCs) were obtained from normal-hearing listeners at probe frequencies between 250 and 8000 Hz. The short probe tones were fixed in level (∼10-dB SPL). The level of the preceding forward masker was adjusted to obtain masked threshold as a function of the time delay between masker and probe. These isoresponse TMCs were obtained for an on-frequency masker, where the masker frequency (Fm) and probe frequency (Fp) were the same, and for an off-frequency masker below the probe frequency (Fm = 0.6Fp). Slopes of off-frequency TMCs for probe tones at 250–1000 Hz were steeper than those for probe tones between 2000 and 4000 Hz, supporting the notion that response growth for Fm = 0.6Fp at lower probe frequencies is not linear. Therefore, a group average off-frequency TMC slope, for probe frequencies between 2 and 4 kHz, was used to calculate response growth at every probe frequency. Input/output response growth curves were derived from the TMCs, and response growth rates were calculated as a function of the masker level in individual ears. At any particular probe frequency, response growth rates varied with input level, from near 1.0 at low input levels, to <0.2 at mid levels, and back to near 1.0 at levels above 80-dB SPL. It was concluded that compression is equally strong at low and high frequencies as it is at mid frequencies. © 2004 Acoustical Society of America.
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43.10.Km Patents

The temporal effect with notched-noise maskers: Analysis in terms of input–output functions

Elizabeth A. Strickland

J. Acoust. Soc. Am. Volume 115, Issue 5, pp. 2234-2245 (2004); (12 pages) | Cited 14 times

Online Publication Date: 16 Apr 2004

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This study examines whether a temporal masking effect may be consistent with a decrease in gain at the masker frequency during the course of the masker. Threshold level of a long-duration notched-noise masker needed to mask a 1- or 4-kHz signal was measured for three conditions: a short-duration signal with a short delay or a long delay from masker onset, and a long-duration signal. The difference between threshold for the long-delay signal and the short-delay signal was defined as the temporal effect. The size of the temporal effect depended on signal frequency, signal level, and masker notch width. Filters estimated from the data had narrower bandwidths for the long-delay condition than for the short-delay condition or the long-duration condition, which seems inconsistent with the hypothesis of a decrease in gain. However, modeling of the data in terms of basilar-membrane input–output functions is consistent with a decrease in gain in the masker frequency region during the course of the masker. For a notch width of 0.0 the results are consistent with a decrease in gain at the signal frequency. For a relative notch width of 0.4, the decrease in gain at the masker frequency may cause a decrease in the suppression of the signal. This decrease in suppression could explain the decrease in filter bandwidth with signal delay. © 2004 Acoustical Society of America.
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43.66.Dc Masking
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Ba Models and theories of auditory processes

Effect of number of masking talkers and auditory priming on informational masking in speech recognition

Richard L. Freyman, Uma Balakrishnan, and Karen S. Helfer

J. Acoust. Soc. Am. Volume 115, Issue 5, pp. 2246-2256 (2004); (11 pages) | Cited 37 times

Online Publication Date: 16 Apr 2004

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Three experiments investigated factors that influence the creation of and release from informational masking in speech recognition. The target stimuli were nonsense sentences spoken by a female talker. In experiment 1 the masker was a mixture of three, four, six, or ten female talkers, all reciting similar nonsense sentences. Listeners’ recognition performance was measured with both target and masker presented from a front loudspeaker (F–F) or with a masker presented from two loudspeakers, with the right leading the front by 4 ms (F–RF). In the latter condition the target and masker appear to be from different locations. This aids recognition performance for one- and two-talker maskers, but not for noise. As the number of masking talkers increased to ten, the improvement in the F–RF condition diminished, but did not disappear. The second experiment investigated whether hearing a preview (prime) of the target sentence before it was presented in masking improved recognition for the last key word, which was not included in the prime. Marked improvements occurred only for the F–F condition with two-talker masking, not for continuous noise or F–RF two-talker masking. The third experiment found that the benefit of priming in the F–F condition was maintained if the prime sentence was spoken by a different talker or even if it was printed and read silently. These results suggest that informational masking can be overcome by factors that improve listeners’ auditory attention toward the target. © 2004 Acoustical Society of America.
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43.66.Dc Masking
43.66.Pn Binaural hearing
43.66.Qp Localization of sound sources

Dominance of missing fundamental versus spectrally cued pitch: Individual differences for complex tones with unresolved harmonics

Remco Renken, J. Esther C. Wiersinga-Post, Sonja Tomaskovic, and Hendrikus Duifhuis

J. Acoust. Soc. Am. Volume 115, Issue 5, pp. 2257-2263 (2004); (7 pages)

Online Publication Date: 16 Apr 2004

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In a two-alternative, forced-choice experiment, subjects had to compare the pitches of two sounds, A and B. Each sound was composed of four successive harmonics of a fundamental frequency between 100 to 250 Hz, added in cosine or Schröder phase. The harmonic frequencies of A were lower than those of B; the missing fundamental frequency of A was higher than that of B. The dominance of the missing fundamental versus the spectrally cued pitch—a pitch percept corresponding to spectral components—was measured as a function of nA, the lowest harmonic in A. The pitch percept is dominated by the missing fundamental if the harmonics are resolved (nA<7). If the harmonics become unresolved and are added in Schröder phase, the dominance shifts to a spectrally cued pitch (7<nA<13; 75% of the subjects). In the cosine phase condition, many subjects could detect the fundamental pitch well into the unresolved harmonic range (nA>20). For others, the transition was in the realm of partly resolved harmonics. This shows that the temporal envelope modulation of stimuli with only four unresolved harmonics can give a relatively clear fundamental pitch percept. However, this percept varies considerably among subjects. © 2004 Acoustical Society of America.
Show PACS
43.66.Hg Pitch
43.66.Nm Phase effects
43.66.Lj Perceptual effects of sound
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