Sone

The sone is a unit of perceived loudness after a proposal of S. Smith Stevens in 1936. In acoustics, loudness is a subjective measure of the sound pressure. One sone is equivalent to 40 phons, which is defined as the loudness of a 1 kHz tone at 40 dB SPL. The number of sones to a phon was chosen so that a doubling of the number of sones sounds to the human ear like a doubling of the loudness, which also corresponds to increasing the sound pressure level by 10 dB, or increasing the sound pressure by a factor 3.16 (=sqrt{10}). At frequencies other than 1 kHz, the measurement in sones must be calibrated according to the frequency response of human hearing, which is of course a subjective process. The study of apparent loudness is included in the topic of psychoacoustics.

See also

• Weber-Fechner law