Auditory filters respond asymmetrically, favoring frequencies below center
Evidence
The second important factor in such systems is the frequency resolution. We have seen that the critical bands provide a good first approximation for frequency resolution. Actually, slopes of critical-band filters are not infinitely steep but finite, and can be approximated by the steepness of 27 dB/Bark towards low critical-band rates (low frequencies). Towards larger criticalband rates (higher frequencies), the slope depends on level and decreases with increasing level from about 27 dB/Bark to 5 dB/Bark over the 60-dB range above 40 dB. In total, the frequency selectivity of our hearing system can be approximated by the excitation level versus critical-band rate pattern. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1124
Masking can be thought of as the filter’s effectiveness in analyzing a component at its center frequency (maskee) being reduced to some degree by the presence of another com ponent (masker) whose frequency falls within the filter’s response curve. The degree to which the filter’s effectiveness is reduced is usually measured as a shift in hearing thresh old, or “masking level,” as illustrated in Figure 5.9(a). The figure shows that the asymmetry of the response curve results in the masking effect being considerably greater for maskees which are above rather than those below the frequency of the masker. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1635
The dependence of masking on the frequencies of masker and maskee can be illustrated by reference to Figure 2.9, in which an idealized frequency response curve for an auditory filter is plotted. The filter will respond to components in the input acoustic signal that fall within its response curve, whose bandwidth is given by the critical bandwidth for the filter’s center frequency. The filter will respond to components in the input whose frequencies are lower than its center frequency to a greater degree than components that are higher in frequency than the center frequency due to the asymmetry of the response curve. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1594
The dependence of masking on the frequencies of masker and maskee can be illustrated by reference to Figure 2.9 in which an idealized frequency response curve for an auditory filter is plotted. The filter will respond to components in the input acoustic signal which fall within its response curve, whose bandwidth is given by the critical bandwidth for the filter’s center frequency. The filter will respond to components in the input whose frequencies are lower than its center frequency to a greater degree than components which are higher in frequency than the center frequency due to the asymmetry of the response curve. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1634
Categorization
- DEFINE: Gives quantified slopes for auditory critical-band filter asymmetry, a core psychoacoustic model parameter.
- XREF: Connects to critical band theory and the excitation pattern model common across the book’s masking chapters. — connects to: Increasing stimulus level broadens auditory filters and causes upward spread of masking; Gammatone filters match the auditory nerve’s measured impulse response; The ear’s frequency response is level-dependent, favoring mid frequencies at low volume (+4 more)
- corroborated: 8 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1124; David Howard, Jamie Angus, coustics and Psychoacoustics, 1635; David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1594 (+1 more)