Loudness Scales: Phons and Sones

The sone is a perceptual comparative loudness scale relative to a 1000 Hz sinewave at 40 dB, i.e.,

$\displaystyle 1$ sone $\displaystyle \triangleq 40$ phons $\displaystyle ,$

Doubling the number of sones doubles the loudness.

**Figure 2:** Loudness in sones versus loudness level in phons at 1000 Hz.
$\scalebox{0.5}{\includegraphics{eps/phonsSones.eps}}$

The curve has a 10-dB slope with a doubling of loudness.

Similar curves have been measured for several frequencies across the audio range and have, in most cases, yielded the same shape.

``Music 175: Loudness'' by Tamara Smyth, Department of Music, University of California, San Diego (UCSD).