a unit of loudness level of sound (apparent, subjective sound level); defined as loudness of 1000 Hz sound at the sound pressure level of 20 µPa. See also: sone. loudness sound pressure level linguistics : phonetics noun
The unit of subjective sound level. Defined such that the sound level in phones equals the level in SPL for a 1000 Hz tone. Generally used in tests where listeners are asked when a tone at a different frequency sounds as loud as a 1000 Hz tone, to define the subjective frequency response of the ear. See discussion in the text on music and ears.
Loudness contours. A subjective impression of equal loudness by listeners as a function of frequency and sound level (dB). An increase in low frequency sound will be perceived as being much louder than an equivalent high frequency increase.