Sound The human impression of the strength of a sound depends, among other things, on the frequency of the sound. The loudness level of a sound, in phons, is the decibel level of an equally loud 1000 Hz tone. The sone is another unit of comparative loudness. The table below lists some equivalent values of phons and sones. Find an equation that gives the phon level of a sound in terms of the number of sones.
