Reversing the phase of a single harmonic can drastically change its perceived loudness

Evidence

In anechoic listening to buzzy signals, minimal changes in group delays may be audible. This has already been demonstrated with a sawtooth wave, modified by a group delay smooth with frequency, but containing local abrupt change. In the top-left and top-right cases in Figure 11.11, the amplitude spectra are otherwise equal, but the phase of one harmonic has been reversed. This corresponds to applying a group delay of only 0.32 ms at 3100 Hz and none at other frequencies, making that frequency much louder. Such frequency-dependent variations in an otherwise smooth group delay can thus have a large effect during anechoic or headphone listening. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1282

Categorization

• QUESTION: Which sounds count as ‘buzzy’ with this sensitivity, and do real signals like speech ever have such phase structure?
• corroborated: 2 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1282
• XREF: connects to: The power spectrum is blind to the relative phase of a sound’s components; Unresolved harmonics smear together as frequency rises