Explanation

While most audio engineers are familiar with the A-weighting curve, which was based on the 40 phon equal-loudness contour derived initially by Fletcher and Munson (1933) the later CCIR-468 weighting curve, now supported as an ITU standard is less well known outside of the UK and Europe. Originally incorporated into an ANSI standard for sound level meters, A-weighting was never specifically intended for the measurement of the more random (near-white or pink) noise in electronic equipment, though it came to be used for this purpose.^{[citation needed]} It is now known that the human ear responds quite differently to random noise, and it is this difference that gave rise to the 468-weighting, which became widely used by broadcasters throughout Britain, Europe, and former British Commonwealth countries, where engineers were heavily influenced by BBC test methods.