Joshua G Bernstein

Publications (2)3.1 Total impact

• Article: The role of temporal fine structure in speech source segregation.

  Joshua G Bernstein, Kenneth W Grant
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  ABSTRACT: Normal-hearing (NH) listeners show better speech recognition when a stationary noise masker is replaced by an opposite-gender competing talker at the same signal-to-noise ratio (SNR). Hearing-impaired (HI) listeners often do not show this interfering-talker benefit (ITB). This may be due to a reduced ability to use temporal fine structure (TFS). Consistent with this idea, NH listeners also show little ITB when TFS is removed. We hypothesized that TFS underlies the ITB by providing source-segregation cues. To test this hypothesis, non-auditory segregation cues were introduced in the form of a video of the talker's face. Speech intelligibility was estimated in NH listeners as a function of SNR for sentences spoken by a female talker and masked by speech-spectrum shaped stationary noise or a single male talker. Target and masker were summed before processing by a 15-channel noise vocoder to remove TFS, and presented with or without accompanying video. Without video, listeners received little ITB, consistent with previous results. Auditory-visual conditions yielded as much as 9 dB of ITB, supporting the hypothesis that a diminished ability to perceptually segregate sources contributes to the lack of ITB in the absence of TFS. Similar results were obtained for unprocessed speech in HI listeners.
  The Journal of the Acoustical Society of America 06/2008; 123(5):3711. · 1.55 Impact Factor
• Source

  Available from: umn.edu

  Article: Pitch discrimination of diotic and dichotic tone complexes: harmonic resolvability or harmonic number?

  Joshua G Bernstein, Andrew J Oxenham
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  ABSTRACT: Three experiments investigated the relationship between harmonic number, harmonic resolvability, and the perception of harmonic complexes. Complexes with successive equal-amplitude sine- or random-phase harmonic components of a 100- or 200-Hz fundamental frequency (f0) were presented dichotically, with even and odd components to opposite ears, or diotically, with all harmonics presented to both ears. Experiment 1 measured performance in discriminating a 3.5%-5% frequency difference between a component of a harmonic complex and a pure tone in isolation. Listeners achieved at least 75% correct for approximately the first 10 and 20 individual harmonics in the diotic and dichotic conditions, respectively, verifying that only processes before the binaural combination of information limit frequency selectivity. Experiment 2 measured fundamental frequency difference limens (f0 DLs) as a function of the average lowest harmonic number. Similar results at both f0's provide further evidence that harmonic number, not absolute frequency, underlies the order-of-magnitude increase observed in f0 DLs when only harmonics above about the 10th are presented. Similar results under diotic and dichotic conditions indicate that the auditory system, in performing f0 discrimination, is unable to utilize the additional peripherally resolved harmonics in the dichotic case. In experiment 3, dichotic complexes containing harmonics below the 12th, or only above the 15th, elicited pitches of the f0 and twice the f0, respectively. Together, experiments 2 and 3 suggest that harmonic number, regardless of peripheral resolvability, governs the transition between two different pitch percepts, one based on the frequencies of individual resolved harmonics and the other based on the periodicity of the temporal envelope.
  The Journal of the Acoustical Society of America 07/2003; 113(6):3323-34. · 1.55 Impact Factor