Amplitude-modulated broadband noise yields only 15% of a pure tone’s pitch strength.

Evidence

The pitch strength of rectangularly amplitude-modulated broad-band noise can be expected to decrease with decreasing temporal modulation depth, since for very small modulation depth, almost broad-band noise is produced. This produces no pitch, and hence has no pitch strength. For a ratio of burst-to-gap duration of 0.04, up to a temporal modulation depth of 5 dB (degree of modulation 28%), amplitude-modulated broad-band noises elicit no pitch sensation. For larger temporal modulation depth, the pitch strength of amplitude-modulated broad-band noise increases almost linearly. About half of the maximally possible pitch strength is obtained for temporal modulation depths around 20 dB (degree of modulation some 80%), and maximally possible pitch strength is obtained for temporal modulation depths larger than about 30dB (degrees of modulation in excess of 95%). However, it should be noted again that even with very short bursts of broadband noise and with large temporal modulation depth, amplitude-modulated broad-band noise produces a pitch strength which reaches only about 15% of the pitch strength produced by a pure tone. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 863