Narrow-band noise sharpness grows proportionally with critical-band rate up to about 3 kHz

Evidence

Sharpness, the ordinate, is given on a logarithmic scale. The solid curve may be considered as a stimulus versus sensation function for sharpness. For narrow-band noises, sharpness increases with increasing centre frequency. At low centre frequencies, sharpness increases almost in proportion to critical-band rate. This may be seen because the reference point, which belongs to a critical-band rate of 8.5 Bark, gives a sharpness of 1 aCllm, which is about four times larger than that produced by a narrow-band noise centred at 200 Hz, corresponding to 2 Bark and leading to about 0.25 acum. For a critical-band rate of 16 Bark corresponding to a centre frequency of about 3 kHz, a sharpness is reached that is about twice as large as that for I-kHz centre frequency. This means that the proportionality of sharpness and critical-band rate lasts at least up to about :~ kHz. For higher frequcncies, however. where critical-band rate does not ill crease much mort’ because of its limit at 24 Bark, sharpness increases faster than the critical-band rate of the centre frequency of the narrow-hand noise. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1347