sone n : a unit of perceived loudness equal to the loudness of a 1000-hertz tone at 40 dB above threshold
- Rhymes: -əʊn
The sone was proposed as a unit of perceived loudness by S. Smith Stevens in 1936. In acoustics, loudness is the subjective perception of sound pressure. Although defined by Stevens as a unit, it is not one of the SI units. Such units meet the stringent criteria of metrology, which include being realizable in a highly precise and reproducible manner, and so transferable for scientific and industrial purposes in a range of contexts.
According to Stevens' definition, the sone is equivalent to 40 phons, which is defined as the loudness level NL 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 approximately 10 dB, or increasing the mean square sound pressure by a factor 10. At frequencies other than 1 kHz, the measurement in sones must be calibrated according to the frequency response of human hearing, which is a subjective process. The study of apparent loudness is included in the topic of psychoacoustics and employs methods of psychophysics.
To be fully precise, a measurement in sones must be specified in terms of the optional suffix G, which means that the loudness value is calculated from frequency groups, and by one of the two suffixes D (for direct field or free field) or R (for room field or diffuse field).
Examples of sound pressure, sound pressure levels, and loudness in sone
sone in Czech: Son (akustika)
sone in German: Sone
sone in Spanish: Sonio
sone in French: Sone
sone in Italian: Sone
sone in Dutch: Sone
sone in Polish: Son