Excitation slopes become frequency-independent above 200 Hz center frequency

Evidence

A comparison of the slope excitations of the seven narrow-band noises indicates that the lower slope (towards smaller critical-band rates) remains constant independent of centre frequency. The steepness of this slope is about 27 dB/Bark. The upper slopes (towards larger critical-band rates) of the excitations are steeper for low-frequency narrowband noises. Above about 200-Hz centre frequency, however, the upper slopes are again identical. This means that in most cases the shapes of the lower and upper slope can be produced by simply shifting the pattern for Ie = 1 kHz along the abscissa. Threshold in quiet produces a limitation at both low and high frequencies. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 974

Categorization

• XREF: The lower excitation slope being a constant 27 dB per Bark independent of center frequency is a canonical psychoacoustic regularity worth holding alongside masking-pattern data in Fig. 4.3 that the text compares against.