Sharp caustic edges demand frequencies far above human hearing range

Evidence

The unit of sharpness, the acum, is defined such that narrowband noise of width 1 Bark and centre frequency 1 kHz at an SPL of 60 dB produces a sharpness value of 1 acum. Psychoacoustic testing reveals that the level of sound also affects the perceived sharpness, but not very prominently. Increasing the level from 30 dB to 90 dB only doubles the sharpness value (Fastl and Zwicker, 2007, Chapter 9). — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1210 (#complicates, via linked claim)

Categorization

• XREF: connects to: Flat surfaces reflect low-frequency sound specularly but scatter high-frequency sound; Masked-threshold growth for tones deviates sharply from Weber’s law at high frequencies; Sound level has only a weak effect on perceived sharpness — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1210

Related

• Sound level has only a weak effect on perceived sharpness (similarity 0.89)
• Doubling sound level from 30 to 90 dB only doubles perceived sharpness (similarity 0.86)
• Sharpness depends primarily on spectral content, not on level or bandwidth. (similarity 0.85)
• Sharpness changes little with level and bandwidth below one critical band. (similarity 0.85)
• Sharpness depends on the spectral envelope, not fine structure (similarity 0.85)
• Adding lower-frequency sound can decrease perceived sharpness (similarity 0.84)
• Noise bandwidth changes sharpness dramatically across a wide range (similarity 0.83)
• Sharpness is modeled as a weighted first moment of specific loudness (similarity 0.82)
• Sharp-edged phenomena require high-frequency waves far above human hearing (similarity 0.82)
• Perceived sharpness is stable across subjects and rises with spectral centre of gravity (similarity 0.82)
• Sensory pleasantness decreases as sound sharpness increases (similarity 0.82)
• Narrow-band noise sharpness grows proportionally with critical-band rate up to about 3 kHz (similarity 0.82)
• Critical bandwidth marks the perceptual shift from rough to smooth tone resolution (similarity 0.81)
• Roughness grows faster with modulation depth for tones than for noise (similarity 0.81)
• Wider bandwidth increases perceived loudness at equal sound pressure (similarity 0.80)

Broader Connections

• Flat surfaces reflect low-frequency sound specularly but scatter high-frequency sound #qualifies (0.80)
• Sound level has only a weak effect on perceived sharpness #complicates (0.80) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1210
• Masked-threshold growth for tones deviates sharply from Weber’s law at high frequencies #complicates (0.75)