Human audible pressure range spans over a million to one amplitude ratio

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. Thus the sound pressure level (SPL) is defined as: where pactual = the actual pressure level (in Pa) and pref = the reference pressure level (20 μPa) The multiplier of 20 has a twofold purpose. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 193

Categorization

• XREF: The million-to-one range and logarithmic perception tie to the reader’s One Square Inch of Silence material on why we measure in decibels and perceive loudness nonlinearity. — connects to: Human hearing spans a ratio of millions between faintest and painful sound — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 604
• SHARE: The fact that threshold of hearing and pain are exactly a million-to-one apart in pascals is a crisp nerdy stat for someone into audio.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 193