Application of an auditory filter for the evaluation of sounds and sound fields

Auditory filters that simulate function of the human auditory organ are introduced for the evaluation of a sound and sound field. Three applications are discussed in this report. The first examines the similarity of sound fields. Music signals convolved with different impulse responses are compared subjectively and quantitatively. The output of the auditory filter indicated high correlations with subjective evaluation. The second example examines the decay process of the sound field, especially in rather dead conditions. Impulse responses measured in recording studios are passed through both an auditory filter and a conventional band-pass filter. Decay processes are then calculated by inverse integration. The responses after passing through the auditory filter show more stable decay curves and the obtained reverberation times are closer to the early decay time, which is closely related to human perceived reverberance. The timbres of musical instruments are used as the third example. The signals from instruments with different means of sound production (such as reed or mouthpiece) are processed by auditory filters and normal band-pass filters. Statistically-obtained characteristics such as kurtosis of the waveform again show higher correlation with subjective evaluation when employing the auditory filter. All the results shown in this report strongly suggest the superiority of an auditory filter in the qualitative evaluation of sounds and sound fields.