The phon is a logarithmic unit of loudness level for tones and complex sounds. Loudness is measured in sone which is a linear unit. Human sensitivity to sound is variable across different frequencies; therefore, although two different tones may present an identical sound pressure to a human ear, they may be psychoacoustically perceived as differing in loudness.

author

by oran collins
github.com/wisehackermonkey
oranbusiness (at symbol)gmail(dot character)com
20210313