Effects of Pure-Tone Masking on Low-Pass- and High-Pass-Filtered Noise

Abstract

Threshold measurements were obtained for low-pass- and high-pass-filtered noises in the presence of pure tones in normal subjects. High-pass-filtered noise with cutoff frequencies at 2400 Hz and above yielded masking peaks near the cutoff frequencies. When noise was filtered with cutoff frequencies at 1200 Hz and below, pure tones of 800 and 1000 Hz had the greatest masking effect. For low-pass-filtered noise, as the bandwidth increased, masking peaks moved from low frequency to high. The masking effect was indistinguishable from that of white noise when filtered noise was cutoff at frequencies of 2400 Hz and above. These results suggest that there is a definite mechanical resonant frequency effect on noise when the width of filtered noise exceeds a critical value. Masking effects are discussed in relationship to mechanical resonant frequency and the interaction of difference and summation tones.