Supplementary Paper No. 3. Masking of Tones by Narrow Bands of Noise

Abstract

The concept of the aural critical band introduced by Fletcher has proved to be very useful in interpreting masking phenomena in many Naval applications, as well as others. The validity of this concept rests in a large measure on the behavior of the masked threshold for pure tones masked by bands of noise narrower than the width of the critical band. In order to gather additional data in this region, narrow bands of noise having perfectly sharp edges were synthesized by superposition of single-frequency tones spaced approximately one c.p.s. apart. These bands of widths 8, 16, 32, 48, and 96 c.p.s. were used to mask pure tones centered in the band. All five band-widths were studied at 200, 800, and 3200 c.p.s. for 20 observers. The results support Fletcher's finding that, for noise bands narrower than the critical band, a pure tone at the center of the band becomes audible when its intensity equals that of the noise.