Loudness growth with intensity requires experimental quantification, not intuition

Evidence

Intensity, while it has concrete bearing on what sound will do to the hearing apparatus, is not the same metric as perceived loudness, which doubles with every ten-decibel increase, so that going from 40 to 50 decibels equals a rise of 100 percent. — George Michelsen Foy, Zero Decibels, 53 (#corroborates, via linked claim)

Although the perceived loudness of an acoustic sound is related to its amplitude, there is not a simple one-to-one functional relationship. As a psychoacoustic effect, it is affected by both the context and nature of the sound. It is also difficult to measure because it is dependent on the interpretation by listeners of what they hear. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 616 (#corroborates, via linked claim)

Categorization

• XREF: connects to: Noise reduction claims should use loudness ratios to stay credible — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1782; Loudness scales with frequency squared, requiring large amplitude at low frequencies; A tenfold intensity increase is perceived as only twice as loud — Eric J. Heller, Why You Hear What You Hear- An…, 143 (+8 more)

Related

• Loudness is perceptual and unmeasurable directly, while intensity is acoustic and directly quantifiable (similarity 0.92)
• Loudness depends on more than physical sound intensity alone (similarity 0.90)
• Lack of intensity-measuring instruments shaped early psychoacoustic research priorities (similarity 0.90)
• Loudness perception requires a tenfold intensity increase to double (similarity 0.90)
• Perceived loudness doubles with every 10 dB increase, not every 3 dB of intensity. (similarity 0.89)
• Sound intensity level and sound pressure level are roughly equivalent (similarity 0.89)
• Loudness perception is essentially logarithmic (similarity 0.88)
• Loudness scales with frequency squared, requiring large amplitude at low frequencies (similarity 0.88)
• A tenfold intensity increase is perceived as only twice as loud (similarity 0.88)
• Loudness depends on frequency, angle, duration, and envelope, not just level (similarity 0.87)
• Perceived loudness does not map one-to-one onto acoustic amplitude (similarity 0.87)
• Doubling perceived loudness requires a 10 dB increase. (similarity 0.87)
• A 10 dB increase always doubles perceived loudness above 40 dB (similarity 0.87)
• Perceived loudness and physical sound intensity follow different, non-intuitive mathematical scales (similarity 0.86)
• Loudness perception is logarithmic, which is why decibel scales fit hearing so well. (similarity 0.86)

Broader Connections

• Perceived loudness and physical sound intensity follow different, non-intuitive mathematical scales #corroborates (0.90) — George Michelsen Foy, Zero Decibels, 53
• Perceived loudness does not map one-to-one onto acoustic amplitude #corroborates (0.80) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 616
• Loudness-growth slope increases with hearing-loss degree but resists exact prediction #corroborates (0.75)