Interaural level differences and time shifts trade off to cancel each other

Evidence

Because both intensity and delay cues are used for the perception of sound source direction, one might expect the mechanisms to be in similar areas of the brain and linked together. If this were the case, one might also reasonably expect that there was some overlap in the way the cues were interpreted such that intensity might be confused with delay and vice versa in the brain. This allows for the possibility that the effect of one cue, for example delay, could be canceled out by the other, for example intensity. This effect does in fact happen and is known as “interaural time difference versus interaural intensity difference trading.” In effect, within limits, an interaural time delay can be compensated for by an appropriate interaural intensity difference, as shown in Figure 2.30, which has several interesting features. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 740

There is a trade-off between interaurallevel differences and interaural time shifts. This means that a shift of the sound image towards the right, obtained by presenting the sound to the right earphone earlier, can be shifted back to a centre image by presenting the sound to the left earphone at a higher level. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1716

Categorization

• DEFINE: Introduces the term ‘ITD-vs-IID trading’ with a clear mechanism.
• XREF: A beautiful example of a physical correlation trading off against a time-based one — echoes psychophysical cue-integration themes across perception. — connects to: Directional hearing rests on interaural time and intensity differences. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 704; Interaural time and intensity cues can cancel each other in direction perception. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 740
• corroborated: 3 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 740; Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1716