Listeners prefer flat amplitude response but are insensitive to phase shift

Evidence

An enormous amount of evidence indicates that listeners are attracted to linear (flat and smooth) amplitude vs. frequency characteristics; more to be shown later. Figure 7 in Toole (1986) and the excerpts shown here in 270. Figure 2.4 indicate that listeners showed a clear preference for loudspeakers with smooth and flat frequency responses. Figure 2.4 also shows phase responses for those same loudspeakers. It is difficult to see any reliable relationship to listener preference, except that those with the highest ratings had the smoothest curves, but linearity did not appear to be a factor. Listeners were attracted to loudspeakers with minimal evidence of resonances because resonances show themselves as bumps in frequency response curves and rapid up-down deviations in phase response curves. The most desirable frequency responses were approximations to horizontal straight lines. The corresponding phase responses had no special shape, other than the smoothness. This suggests that we like flat amplitude spectra, we don’t like resonances, but we seem to be insensitive to general phase shift, meaning that waveform fidelity is not a requirement. — Toole, Floyd E, Sound reproduction- the acoustics and…, 969

Categorization

• XREF: Connects to the reader’s psychoacoustic modeling focus: waveform fidelity and phase audibility are central to models of perceived sound quality.
• SEED: Angle for an article or essay: ‘we like flat amplitude, we don’t like resonances, we seem insensitive to phase shift’ — a compact distillation of what actually matters in loudspeaker design versus engineering fetishism about waveform integrity.