Phon

A phon is a unit used to measure the perceived loudness of a sound to the human ear. It compares different sounds to a standard where 1000 Hz tone at 40 decibels is defined as 40 phons. Basically, if a sound’s loudness matches the perceived loudness of a 1000 Hz tone at a certain decibel level, that level in phons indicates its loudness. The phon scale helps quantify how loud a sound seems to human listeners, considering both intensity and frequency, making it a useful tool in acoustics and audio engineering.