Permissible value of group delay distortion on tone quality due to low-pass filters

Generally, in low-pass filters with very steep attenuation characteristics, group delay distortion occurs near the cut-off frequency. As a result, it is seen that the group delay distortion has a distinct influence on tone quality. Consequently, we have examined degradation of tone quality due to group delay distortion from low-pass filters, and from the results of our experiments, it has been verified that the permissible value of group delay distortion on tone quality due to low-pass filters is about 2 ms, in the high frequency range. In digital audio systems, low-pass filters with very steep attenuation characteristics (for example, Chebyshev-type filters) have been usually used to minimize aliasing noise and eliminate higher harmonic components. Then, we have verified the permissible value of the attenuation characteristics of low-pass filters in digital audio systems, from the results of the permissible value of group delay distortion on tone quality due to low-pass filters.