The detectability of clicks at onset or offset of brief bands of noise is measured as a function of the Sensatin Level(SL) of the signals ranging from 30 to 70 dBSL. The bandwidths are 0. 5, 1, 5, 10 and 24 critical bandwidths(CBW) cetered at 1950 Hz respectively, and each signal has a trapezoidal envelope. The results show that the critical rise or decay time (tc_1, tc_2) required to achieve clickless signal depends on the level and the bandwidth. As a band of noise is widened, the transient clicks are less audible, so that any click can not perceived for a broadband noise. The average data can well be approximated by the equation (I/I_0)・tc^<αj>_j=constant, where I and I_0 are instensity of the signal and its threshold respectively, α_j is a constant depending on the bandwidth, and tc_j is the critical rise (j=1) or the decay (j=2) time. This is the same equation as given for a sinusoidal signal. It is also shown that there exists temporal masking at transient parts of the signal. From above results, a mechanism of the perception of clicks is discussed, and it is suggested that only the upper or lower skirts of the transient excitation pattern at onset or offset of the bands of noise can contribute to the perception of clicks.
抄録全体を表示