unit for measuring the loudness of a sound
Common clues: Unit
of loudness; Loudness measure; Sound unit; 40-decibel unit;
2 times a year
– Acoustic Curves
sone was proposed as a unit of perceived loudness by Stanley
Smith Stevens in 1936. In acoustics, loudness is the subjective
perception of sound intensity. Although defined by Stevens as a
unit, it is not one of the SI units.
to Stevens' definition, a loudness of 1 sone is equivalent to the
loudness of a signal at 40 phons, the loudness level of a 1 kHz
tone at 40 dB SPL. But phons scale with level in dB, not with
loudness, so the sone and phon scales are not proportional.
Rather, the loudness in sones is, at least very nearly, a power
law function of the signal intensity, with an exponent of 0.3.
With this exponent, each 10 phon increase (or 10 dB at 1 kHz)
produces almost exactly a doubling of the loudness in sones.
frequencies other than 1 kHz, the loudness level in phons is
calibrated according to the frequency response of human hearing,
via a set of equal-loudness contours, and then the loudness level
in phons is mapped to loudness in sones via the same power law.
study of apparent loudness is included in the topic of
psychoacoustics and employs methods of psychophysics.
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