AS 3657.1-1989

Specifies the relations existing, for the condition of equal-loudness level, between the sound pressure levels and frequencies of pure (sinusoidal) continuous tones in the different conditions. The relations are expressed by means of an equation in bilinear form, for the preferred frequencies in the one-third octave series from 20 Hz to 12 500 Hz inclusive. It is based on ISO 226:1987.