The Effect of Attenuation Rate and Peak Bandwidth of Tonal Components on Perceived Tonalness

Band-pass filtered noise can be perceived to some degree as tonal. The perceived strength of this tonal quality depends on the spectral shape of the filtered noise and the presence of other features in the total sound. The spectral shape of bandpass filtered noise can be characterized by the center frequency, bandwidth, and roll-off rate of the filter. In order to determine the interaction between bandwidth and roll-off rate for band-pass filtered noise, the tonalness of band-passfiltered noise was evaluated by using three test methods: paired comparison, direct scaling, and an adaptive forced choice method. All three test methods yielded very similar results. Trapezoidal band-pass filtered random noise was used for the experiments. For a roll-off rate of 300 dB per octave, the tonalness of the sounds ranged from 30 to 90 percent of a pure tone's tonalness for a bandwidth of 300 to 1 percent of the critical bandwidth. For a roll-off rate of 100 dB per octave, the tonalness of the sounds ranged from 30 to 60 percent of a pure tone's tonalness. As the roll-off rate of the filtered sounds approachedzero, the tonalness disappears.