Index of content:
Volume 113, Issue 5, May 2003
- PSYCHOLOGICAL ACOUSTICS 
113(2003); http://dx.doi.org/10.1121/1.1547438View Description Hide Description
The auditory system encodes the timing of peaks in basilar-membrane motion with exquisite precision, and perceptual models of binaural processing indicate that the limit of temporal resolution in humans is as little as 10–20 microseconds. In these binaural studies, pairs of continuous sounds with microsecond differences are presented simultaneously, one sound to each ear. In this paper, a monaural masking experiment is described in which pairs of continuous sounds with microsecond time differences were combined and presented to both ears. The stimuli were matched in terms of the excitation patterns they produced, and a perceptual model of monaural processing indicates that the limit of temporal resolution in this case is similar to that in the binaural system.
Testing the concept of a modulation filter bank: The audibility of component modulation and detection of phase change in three-component modulators113(2003); http://dx.doi.org/10.1121/1.1564020View Description Hide Description
Two experiments were performed to test the concept that the auditory system contains a “modulation filter bank” (MFB). Experiment 1 examined the ability to “hear out” the modulation frequency of the central component of a three-component modulator applied to a 4-kHz sinusoidal carrier. On each trial, three modulated stimuli were presented. The modulator of the first stimulus contained three components. Within a run the frequencies of the outer two components were fixed and the frequency of the central (“target”) component was drawn randomly from one of five values. The modulators of second and third stimuli contained one component. One had a frequency equal to that of the target and the other had a frequency randomly selected from one of the other possible values. Subjects indicated whether the target corresponded to the second or third stimulus. Scores were around 80% correct when the components in the three-component modulator were widely spaced and when the frequencies of the target and comparison differed sufficiently. Experiment 2 examined the ability to hear a change in the relative phase of the components in a three-component modulator with harmonically spaced components, using a 3IFC task. The frequency of the central component, was either 50 or 100 Hz. Scores were 80%–90% correct when the component spacing was but decreased markedly for greater spacings. Performance was only slightly impaired by randomizing the overall modulation depth from one stimulus to the next. The results of both experiments are broadly consistent with what would be expected from a MFB with a Q value of 1 or slightly less.