[OT] Decibels and the ear [was: Re: [plug] Hot and bothered CPU hankers for cool breeze]

[Mike Holland]

On Wed, 17 Dec 2003, James Devenish wrote:

> > lost. 400 fans are 400x louder.
>
> Well no. This is what I was saying (but I didn't realise Cameron had
> beat me to it). 400 fans produce 400 times the noise. But whether that
> is 400x *louder* is a consequence of our physiology (or physio-

I'm not sure I agree. If you want to know when two notes of different
pitch are the same loudness, thats physiology. But what does it mean to
say one noise is twice as loud as another? If you asked to turn the
volume knob "twice as loud", would people act consistently?
  The only sensible interpretation of "n times as loud" I can think of, is
to say it "sounds as if there are n times as many sources". The problem
is, we rarely have the chance to hear such comparisons, and judgement is poor.

  Compare to lighting. What would happen is we increased the lighting
1000x in a typical office? People might expect to burn up, but actually,
it would be about the same as normal sunlight. Is that a case of perceived
brightness different to measured, or just lack of a scale of reference?

> There are "units", such as phons and sones, that are determined
> empirically to describe the relationships between the physical
> phenomenon of sound and its perceptual consequences at different
> frequencies and intensities.

Isnt that more about comparing volume at different frequency combinations?
(and on a log scale)