Loudness

We subjectively assign a loudness to a given intensity of sound of a certain frequency.

To quantify loudness is used the unit phon (Ph), which has been determined by measuring curves of equal loudness levels (isophons) in healthy subjects. Each curve corresponds to the same auditory perception at different frequencies. The number of phons was assigned to each curve according to the number of dB at frequency 1 kHz.

Thus, the loudness level for any tone is determined by varying the intensity of the reference tone (f = 1 kHz) until it has the same loudness as the tone to be determined. The number of phons of the tone equals the number of absolute dB of the reference tone.

Related articles

 * Hearing Field

External sources

 * Loudness (english wikipedia)