Masking of Transient Signals Having Identical Energy Spectra

Abstract

Pairs of waveforms having identical energy spectra were generated using a technique developed by Huffman. A pair of such waveforms differ only in their phase spectra. The discriminability of such waveforms was measured under various conditions. The total duration of the waveforms was varied as well as the nature of the differences in their phase spectra. The results of these experiments suggest that the ear can discriminate differences in temporal order as small as 2.5 msec. In latter experiments this discriminability among pairs was studied when both waveforms were partially masked by noise. Some pairs can be discriminated when only 6 dB above their masked threshold. These same waveforms were used in a series of masking experiments. When these waveforms are used as maskers of sinusoidal signals they do not produce equal masking, although the energy in any region near the signal frequency is the same for all maskers. The masked threshold for the sinusoids changes as much as 15 dB as a function of the part...