Webster's English Dictionary

Enter the word to look up:

phon

phon \'fa:n\ n [ISV, fr. Gk pho-ne- voice, sound] : the unit of loudness 
   level on a scale beginning at zero for the faintest  audible sound and 
   corresponding to the decibel scale of sound intensity with the number of 
   phons of a given sound being equal to the decibels of a pure 1000-cycle 
   tone judged by the listener to be equally loud