SN A Wieghted

when a s/n ratio is quoted as being A weighted, does that mean it is class A or something else?

 

Andy,

'A' weighted is an industry standard test, although a possibly dubious one
Figures again Andy, I don't know what happened to those ears

 

LoL

Still useing ears mate
Just had no idea of what it meant

 

A weighting is a means of specifying noise & THD after it has been filtered to reflect the response of the human ear. Of course, A weighting does not alter with sound level as the ears response does, so A weighting, while relevent at listening level of around 60dB SPL (typical conversational level) while not at all relevent at 110dB SPL (typical maximum concert level).

As a rule of thumb, W weighting gets you around 10dB extra signal to noise ration to write on your spec sheet.

 

"A" weighted is used in industry to indicate the "nuisance" factor of the noise. What it actually mimics is the sensitivity of the ear/brain to the frequency spectrum. So a 3khz tone will measure louder than a 500hz tone of the same actual pressure level on an "A" weighted setting. Where as using an "unweighted" measurement will show the same levels for both frequencies. This is because the ear/brain hears some frequencies louder than others for the same actual level. In industry/offices etc.. "A" weighting measurements are taken so that an "accurate" measure of a noises "irritation" is known.

"A" weighted measurements have no justifiable use in Hi-Fi. It is a measure of "perceived" loudess, not actual accuracy of reproduction.

GTM

 

Depends on how loud you listen.
At around 60dB spl, A-weighting is a fair approximation of the response of the hearing system. So is a good indication of how loud different frequency components sound.

At higher sound pressure levels, the hearing system flatens out (not accounting for age or damage related hearing loss) until at about 110dB spl, the ear has a flat response, and A-weighting is irrelevant.