Phon


 * Phon is also the name of a town in Thailand.



The phon is a unit of perceived loudness level LN for pure tones. The purpose of the phon scale is to compensate for the effect of frequency on the perceived loudness of tones. By definition, 1 phon is equal to 1 dBSPL at a frequency of 1 kHz. The Fletcher-Munson curves are a way of mapping the dBSPL of a pure tone to the perceived loudness level in phons.

The phon model can be extended with a time-varying transient model which accounts for "turn-on" (initial transient) and long-term, listener fatigue effects. This time-varying behavior is the result of psychological and physiological audio processing.