Raising noise level paradoxically worsens cut-off frequency discrimination as upper slopes flatten.

Evidence

As indicated by the inset of Fig. 7.21, the upper slopes of the excitation patterns become flatter with increasing level of the low-pass noise. Because the only variation of excitation level - besides the fluctuation of the noise - is that of the upper slope, the deviation of the cut-off frequency has to become larger for increasing level, in order to reach the criterion corresponding to the just-noticeable increment in excitation level. The just-noticeable frequency modulation, 2£1/, of the cut-off frequency of the low-pass noise was measured as a function of the level of the low-pass noise. The curve outlined in Fig. 7.21 indicates a result that may at first be unexpected, but that is predicted by the model. Although the level increases, the sensitivity of our hearing system to changes of the cut-off frequency of the low-pass noise decreases, 7. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1145

Categorization

• QUESTION: The passage trails off at the end — worth chasing the actual measured curve and its quantitative values in Fig. 7.21.