Fluctuation Strength of Modulated Tones and Broadband Noise

Abstract

Modulation of a sound elicits one of two different,kinds of auditory sensation, depending on the speed of modulation. In the case of low modulation frequencies (typically less than about 20 Hz) the resultant sensation is called fluctuation strength (see Terhardt, 1968). Faster modulation of sounds leads to the perception of roughness (v. Békésy, 1935). As yet, fluctuation strength has received considerably less attention than roughness. Terhardt (1968) and Schone (1979) studied the dependence of fluctuation strength on some essential signal parameters, using sinusoidally amplitude modulated pure tones. We have recently repeated and extended these earlier observations, to include investigations of the fluctuation strength of AM-broadband noise (Fastl, 1982a) and of FM-tones.