Audible pressure range spans over a million to one, forcing a logarithmic scale

Evidence

These two pressures broadly correspond to the threshold of hearing (20 µPa) and the threshold of pain (20 Pa) for a human being, at a frequency of 1 kHz, respectively. Thus, real sounds can vary over a range of pressure amplitudes that is greater than a million to one. Because of this, and because of the way we perceive sound, the sound pressure level is also usually expressed on a logarithmic scale. This scale is based on the ratio of the actual sound pressure to the notional threshold of hearing at 1 kHz of 20 µPa. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 193

Categorization

• DEFINE: Defines sound pressure level in relation to hearing threshold at 1 kHz.
• XREF: Connects to soundscape work on decibel scales and loudness perception from One Square Inch of Silence and The Soundscape.