Loudness grows with bandwidth via area tradeoff except at extreme levels

Evidence

This effect is especially pronounced at medium levels. At very low levels, the slope of the specific-loudness function becomes steep, and therefore the decrement in height is stronger than the increment produced by the extension over the critical-band rate. Therefore, loudness remains constant or even decreases at very low levels as a function of bandwidth. When exceeding the critical bandwidth at very high levels, loudness does not increase strongly; only for bandwidths larger than about an octave, corresponding to three critical bands, does loudness increase. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1288

Categorization

• QUESTION: The level-dependence of bandwidth loudness integration begs explanation in terms of the cochlear excitation slope — worth chasing the mechanistic detail in later chapters.
• corroborated: 2 independent passages support this claim — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1288
• XREF: connects to: Loudness rises once noise bandwidth exceeds the critical band at constant SPL.; Loudness stays constant below critical bandwidth then grows beyond it — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1034; Total loudness is the integral of specific loudness over critical-band rate — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1250 (+7 more)

Broader Connections

• Wider bandwidth increases perceived loudness at equal sound pressure #corroborates (1.00) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 868
• Widening a sound’s bandwidth makes it seem louder at equal total power #corroborates (1.00) — Eric J. Heller, Why You Hear What You Hear- An…, 2008
• Loudness grows when sound energy spills beyond a single critical band #expands (0.90) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 667