Modulation detection of sawtooth-wave modulated tones: Effect of temporal asymmetry.

Large perceptual differences can be observed between ramped and damped sounds. In the present study, the effect of temporal asymmetry on amplitude modulation detection was studied with the use of two types of modulators: a ramped sawtooth wave, characterized by a gradual linear rise in amplitude followed by a sharp drop within each period, and the damped sawtooth wave which is the time reverse of the ramped wave. Results showed that a puretone carrier modulated by these two modulators led to differences in modulation detection thresholds with the damped modulation pattern being easier to detect than the ramped modulation pattern. The size of this effect was also dependent on the modulation rate. A model of auditory processing was proposed to account for the temporal asymmetry in modulation detection with the hypothesis that the asymmetric threshold originated at processing stages more central to the auditory nerve.