phonA unit of loudness of sound. The intensity of sound to be measured is compared by the human ear to a reference tone of 2 × 10-5 pascal sound pressure and 1,000 hertz frequency. The intensity of the reference tone is increased until it appears to be equal in loudness to the sound being measured; the loudness of this sound in phons is then equal to the number of decibels by which the reference tone has had to be increased. Related categories ACOUSTICS AND MUSIC UNITS Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History |