Accurate hearing cannot be acutely sensitive to the relative phase of partials.

Evidence

Suppose one singer is producing a pure partial at 100 Hz, and another several meters away is generating a pure partial a fifth above, at 150 Hz. Two listeners at different locations receive the partials with altered phases since the time delays are different. (The phase shift due to a difference d is distance is 2πd/λ, where λ is the wavelength of the partial in question.) Figure 24.3 shows a numerical simulation of this situation, done in Ripple, resulting in a very different-looking sound trace for the two listeners. Nonetheless, we expect them to hear essentially the same tone and timbre. We come to the conclusion that acute sensitivity to the relative phase of partials would not be a good thing. We would not want the two traces in figure 24.2 or 24.3 to sound as different as they look. — Eric J. Heller, Why You Hear What You Hear- An…, 2215

Categorization

• DEFINE: Shows the concrete 2πd/λ rule for phase shift with distance and why phase insensitivity is evolutionarily necessary for stable timbre perception.
• DEEPTHINKING: The insight that what looks radically different in a waveform trace must sound identical is a deep point about how perception decouples from the physical signal — good material for why-hear-what-we-hear.