Modulation masking produced by second-order modulators.
Recent studies suggest that an auditory nonlinearity converts second-order sinusoidal amplitude modulation (SAM) (i.e., modulation of SAM depth) into a first-order SAM component, which contributes to the perception of second-order SAM. However, conversion may also occur in other ways such as cochlear filtering. The present experiments explored the source of the first-order SAM component by investigating the ability to detect a 5-Hz, first-order SAM probe in the presence of a second-order SAM masker beating at the probe frequency. Detection performance was measured as a function of masker-carrier modulation frequency, phase relationship between the probe and masker modulator, and probe modulation depth. In experiment 1, the carrier was a 5-kHz sinusoid presented either alone or within a notched-noise masker in order to restrict off-frequency listening. In experiment 2, the carrier was a white noise. The data obtained in both carrier conditions are consistent with the existence of a modulation distortion component. However, the phase yielding poorest detection performance varied across experimental conditions between 0 degrees and 180 degrees, confirming that, in addition to nonlinear mechanisms, cochlear filtering and off-frequency listening play a role in second-order SAM perception. The estimated magnitude of the modulation distortion component ranges from 5%-12%.
Füllgrabe
Christian
C
Laboratoire de Psychologie Expérimentale--UMR CNRS 8581, Université René Descartes--Paris 5, 71 avenue Edouard Vaillant, 92774 Boulogne-Billancourt, France. c.fullgrabe@psychol.cam.ac.uk
Moore
Brian C J
BC
Demany
Laurent
L
Ewert
Stephan D
SD
Sheft
Stanley
S
Lorenzi
Christian
C
D000293:Adolescent; D000328:Adult; D003051:Cochlea / Q000502:physiology; D003196:Computer Graphics; D005374:Filtration; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D006801:Humans; D009622:Noise; D017711:Nonlinear Dynamics; D010469:Perceptual Distortion / Q000502:physiology; D010470:Perceptual Masking / Q000502:physiology*; D010897:Pitch Discrimination / Q000502:physiology*; D011571:Psychoacoustics; D013018:Sound Spectrography; D013998:Time Perception / Q000502:physiology