Small bass-level changes strongly alter perceived spectral balance

Evidence

The phon scale is a subjective scale of loudness based on the judgments of listeners to match the loudness of tones to reference tones at 1 kHz. The curve for N phones intersects 1 kHz at N dB(SPL) by definition, and it can be seen that the relative shape of the phon curves flattens out at higher sound levels, as shown in Figure 2.13. The relative loudness of different frequencies is not preserved, and therefore the perceived frequency balance of sound varies as the listening level is altered. This is an effect we have all heard when the volume of a recording is turned down and the bass and treble components appear suppressed relative to the midrange frequencies, and the sound becomes “duller” and “thinner.” — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 626 (#exemplifies, via linked claim)

Categorization

• XREF: connects to: Reduced playback levels cause timbral shifts and lost low bass; Bass accounts for roughly 30 percent of perceived sound quality — Toole, Floyd E, Sound reproduction- the acoustics and…, 813; Listeners perceive bass improvements primarily through reduced spectral bumps, not faster decay (+8 more)

Broader Connections

• Volume changes alter perceived frequency balance, not just loudness #corroborates (0.90)
• Turning down volume suppresses perceived bass and treble relative to midrange #exemplifies (0.85) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 626
• Low-Q subwoofer resonances are audible mainly as spectral balance shifts #exemplifies (0.85)
• Listeners perceive bass improvements primarily through reduced spectral bumps, not faster decay #expands (0.82)
• Weighting-curve blind spots create incentive to over-boost bass #expands (0.80) — , Toole, Floyd E - Sound reproduction-…, 1581
• Bass frequencies need far smaller level changes to halve perceived loudness #expands (0.78) — , Toole, Floyd E - Sound reproduction-…, 333
• Spectral balance errors predict headphone preference ratings independent of resonance Q #corroborates (0.75)
• Reverberant fields typically color perceived sound with excess bass that equalization must fix #exemplifies (0.75)
• Tactile vibration raises perceived loudness and lowers preferred bass levels #qualifies (0.70) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1826