[ fon ]
/ fɒn /


a unit for measuring the apparent loudness of a sound, equal in number for a given sound to the intensity in decibels of a sound having a frequency of 1000 cycles per second when, in the judgment of a group of listeners, the two sounds are of equal loudness.

Nearby words

  1. phoenixville,
  2. phokomelia,
  3. pholidota,
  4. pholus,
  5. phomvihane,
  6. phon-,
  7. phon.,
  8. phonal,
  9. phonasthenia,
  10. phonate

Origin of phon

First recorded in 1930–35, phon is from the Greek word phōnḗ voice



variant of phono- before a vowel: phonic. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for phon

British Dictionary definitions for phon


/ (fɒn) /


a unit of loudness that measures the intensity of a sound by the number of decibels it is above a reference tone having a frequency of 1000 hertz and a root-mean-square sound pressure of 20 × 10 –6 pascal

Word Origin for phon

C20: via German from Greek phōnē sound, voice


abbreviation for

Also: phonet phonetics
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for phon



Variant ofphono-

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for phon


[ fŏn ]

A unit of apparent loudness. The loudness of a signal in phons is equal to the intensity in decibels of a 1,000-hertz tone judged to be as loud as the signal being measured.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.