Estimation of the level and phase of the simple distortion tone the modulation domain.
These experiments were designed to test the idea that nonlinearities in the auditory system can introduce a distortion component into the internal representation of the envelope of a sound, and to estimate the phase of the hypothetical distortion component. In experiment 1, a two-alternative forced-choice (2AFC) task with feedback was used to measure psychometric functions for detecting 5-Hz probe modulation of a 4-kHz sinusoidal carrier in the presence of a masker modulator with components at 50 and 55 Hz (m=0.3 for each component). Performance was measured as a function of the relative phase, delta[symbol see text], of the probe relative to the "venelope" (envelope of the envelope) of the masker. Performance was poorest for delta[symbol see text]= 135 degrees. In experiment 2, delta[symbol see text] was fixed at 135 degrees, m was set to 0.48 for each masker component, and psychometric functions for detecting probe modulation were measured using a 2AFC task without feedback. For small probe modulation depths (m approximately 0.03), the detectability index, d', was consistently negative, consistent with the existence of a weak distortion product which can "cancel" the probe modulation. The distortion component for the conditions of the experiment was estimated to have a phase of about -25 degrees relative to the venelope.
Sek
Aleksander
A
Institute of Acoustics, Adam Mickiewicz University, 61-614 Poznan, Poland.
Moore
Brian C J
BC
D000161:Acoustic Stimulation; D000162:Acoustics; D001307:Auditory Perception / Q000502:physiology*; D006801:Humans; D010469:Perceptual Distortion / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology; D011594:Psychometrics / Q000379:methods*