(Kevin Baker )

Subject: 
From:    Kevin Baker  <klb(at)DE-MONTFORT.AC.UK>
Date:    Fri, 27 May 1994 10:53:04 +0100

This is a general question

The mini-FAQ which was posted recently has just jogged my memory of a
nagging question which I had put to the back of my mind for some time.
Here goes:

It seems to me that trying to get a 'perceptual equivalence' for intensity
and pitch, in the form of equal loudness curves, is always going to be
problematic.

We have evolved to use pitch and loudness as complementary
cues. Saying that a low pitched noise sounds as loud as a high pitched
noise tells us two things:
(1) that the low pitched sound was made by larger and more slowly
vibrating materials on impact;
and (2) that the higher pitched sound is closer (as high frequencies
attenuate with distance).

Of course, pitch is not a sole cue for the nature of the sound making
event (as loudness tells us about the energy and vibratory nature of the
materials involved). Similarly, loudness is not a sole cue for the distance of
the event (as spectral changes can also indicate the direction and
distance). But how can equal loudness curves using simple tones indicate
the perceptual processes which exploit these cues?

In the end, I suppose my query is twofold:
(1) How much does the 'equal loudness' curve vary across individuals and
within individuals during lifespan?
If it varies alot then it can't be THAT important - it may be more
prudent to investigate how we LEARN to use this information by higher level
processes.

(2) How does our knowledge about equal loudness curves allow us to infer
anything more than a basic psycophysical model of hearing simple/pure tones at
varying frequencies and amplitudes?

Or: Have I missed something?


Kevin L. Baker
                           Dept. Human Communication
                           De Montfort University, Leicester, UK
                           Tel: +44 533 577761
                           Fax: +44 533 577708
                           email: k.baker(at)dmu.ac.uk