Main Page | See live article | Alphabetical index The phon is a unit of perceived loudness, which is a subjective measure of the intensity of a sound. At a frequency of 1 kHz, 1 phon is defined to be equal to 1 dB of sound pressure level above the nominal threshold of hearing (1 pW/m²). At other frequencies, the phon departs from the decibel, but is related to it by a frequency weighting curve that reflects the frequency response of human hearing. The standard curve for human hearing is the A-weighted curve, but others are in use. See also: sone This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.