phon

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The phon was proposed^[when?] as a unit of perceived loudness level L_N for pure tones by S. S. Stevens.^[1]

Definition

The purpose of the phon scale is to compensate for the effect of frequency on the perceived loudness of tones.^[2] By definition, 1 phon is equal to 1 dBSPL at a frequency of 1 kHz.^[3]

The equal-loudness contours are a way of mapping the dBSPL of a pure tone to the perceived loudness level in phons. These are now defined in the international standard ISO 226:2003, and the research on which this document is based concluded that earlier Fletcher–Munson curves and Robinson-Dadson curves were in error.^{[citation needed]}

The phon unit is not generally accepted according to the stringent criteria of metrology.^{[clarification needed][citation needed]} It has not been accepted as a standard unit by the United States National Institute of Standards and Technology.^{[citation needed]}

The phon model can be extended with a time-varying transient model which accounts for "turn-on" (initial transient) and long-term, listener fatigue effects. This time-varying behavior is the result of psychological and physiological audio processing. The equal-loudness contours on which the phon is based apply only to the perception of pure steady tones: tests using octave or third-octave bands of noise reveal a different set of curves, owing to the way in which the critical bands of our hearing integrate power over varying bandwidths and our brain sums the various critical bands.^{[clarification needed][citation needed]}

See also

• Sone
• A-weighting

References

External links

• Explanation with definitions