Threshold perception integrates total sound intensity across a limited frequency bandwidth.

Evidence

It is interesting to note that in the range between one and eight tones in the complex, the threshold level decreases 3 dB per doubling of the number of tones. This means that, at threshold, the overall sound pressure level of the complex remains constant regardless of the number of tones. This rule holds only up to about nine tones. Beyond this number, threshold expressed as level of each tone in the complex no longer decreases with increasing number of tones, i.e. overall sound pressure level increases. This means that the threshold in quiet is determined in our hearing system by the sound intensity of the total complex, as long as the components of this complex fall within a certain bandwidth. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 878

Categorization

• DEFINE: Establishes the critical-band integration rule: overall level constancy up to a bandwidth limit, beyond which extra components don’t add to threshold.