The Masking of Clicks by Pure Tones and Bands of Noise

Pure tones and various bands of noise were used to mask impulsive acoustic stimuli (clicks) that were produced by electrical square pulses through a moving‐coil type earphone. Results indicate that it is difficult to generalize about the masking of clicks by pure tones from observations on only a few observers because of sizeable individual differences. The masking of clicks by noise, however, is related unambiguously to the intensity and the spectral distribution of the noise. Both pure tones and narrow bands of noise provide maximum masking in the region between 1000 and 3000 c.p.s. Generally speaking, noise is a more efficient masker of clicks than are single pure tones. Although the present measurements were made with masking frequencies below 6500 c.p.s., there is some preliminary evidence to suggest that the audibility of certain clicks in noise is markedly dependent on frequencies above 6500 c.p.s. The linear (slope = 1) relation between the masking of speech or pure tones by noise and the intensity of the noise does not apply here. Rather a trimodal function indicates that the masking of unfiltered clicks by “pinkish‐white” noise does not change over a 30‐db range of moderate intensities. Below and above this range masking increases with the intensity of noise, sometimes at a slope greater than one.