Hello,

In addition to the Fletcher-Munson equal loudness curves describing our
psycho-acoustic response, are there any curves to describe distortion in the
ears?

ie. Does each set of ears/brain have a second and third order
intermodulation intercept point?

ie. Can you be bombarded with large SPLs of pure sinewaves at 20kHz and
24kHz and perceive 4kHz (F2-F1) and 16kHz (2F1-F2).

I'm sure it's vastly more complicated than this....?

In article , íçëéìèî
wrote:
Hello,

In addition to the Fletcher-Munson equal loudness curves describing our
psycho-acoustic response, are there any curves to describe distortion in
the ears?

ie. Does each set of ears/brain have a second and third order
intermodulation intercept point?

ie. Can you be bombarded with large SPLs of pure sinewaves at 20kHz and
24kHz and perceive 4kHz (F2-F1) and 16kHz (2F1-F2).

I'm sure it's vastly more complicated than this....?

As Arny has said, "yes"... :-)

There are a number of physiological measurements that show things like the
levels of two-tone intermodulation effects in the ear. The real difficulty
is in interpeting the meaning of such measurements as the brain processes
the output of the ear sensor system and the resulting perceptions then
attempts to 'take this into account' in a complex signal-dependent manner.

You don't need either high powers or high freqencies to observe nonlinear
responses in the ear. IIRC many of the papers use just a few kHz.

The papers I have on this are at work. If I remeber to do so, I'll note the
main review paper reference I found and post it later on in case you are
interested.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Jim Lesurf
wrote:


The papers I have on this are at work. If I remeber to do so, I'll note
the main review paper reference I found and post it later on in case you
are interested.

The reference I had in mind is:

Mechanics of the mammalian cochlea
Robles and Ruggero
Physiological Review Vol 81 Number 3 (July 2001) pp 1305 - 52

The above is an excellent review of this area with pages of references to
more detailed papers on all sorts of related topics, including non-linear
effects in hearing.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Arny Krueger" wrote in message ...
(...)
ie. Can you be bombarded with large SPLs of pure sinewaves at 20kHz
and 24kHz and perceive 4kHz (F2-F1) and 16kHz (2F1-F2).

You've got to pick frequencies where the ear actually responds...

I'm not sure that it's been established that the tones must be
~20KHz, i.e., I don't know whether distortion products can
conceivably occur if one (or more) of the tones are 20KHz. I've not
found any research which looks at that (though it would be pretty
simple to run a quick practical test to find this out),but I've not
searched exhaustively.

To obtain (some of) these distortion products does not require large
SPLs. In fact, these ear-based nonlinearities have been used to carry
tunes in (classical) music.

Although these tones are a function of the way the ear initially
amplifies tones, there's recent evidence that these products may be
influenced by attention, i.e. 'higher order' processes can alter the
ear's behaviour (doi: dx.doi.org/10.1017/S0048577201990109).
Interesting.

There's a nice review of this stuff he
http://physrev.physiology.org/cgi/reprint/81/3/1305 (Robles & Rugger
01, Physiol Rev 81: 1305-1352.

Steve.

"íçëéìèî" wrote in message
...
Hello,

In addition to the Fletcher-Munson equal loudness curves describing our
psycho-acoustic response, are there any curves to describe distortion in
the
ears?

ie. Does each set of ears/brain have a second and third order
intermodulation intercept point?

ie. Can you be bombarded with large SPLs of pure sinewaves at 20kHz and
24kHz and perceive 4kHz (F2-F1) and 16kHz (2F1-F2).

I'm sure it's vastly more complicated than this....?



I seem to remember reading about a Korean(?) company experimenting with a
public address system that generated a carrier around 20KHz plus an audio
signal shifted up by 20KHz, the assumption being that the non-linearity of
the ear would make it audible. The transducers were placed in a matrix
several feet above head height, and because of beaming at these frequencies
the sound(!) would appear generally from above. But the last I heard was
that they were experimenting with a membrane above the listener to create
additional non-linearity.

Graham Holloway

On Wed, 16 Jul 2003 16:34:34 +0100, "Graham Holloway"
wrote:

I seem to remember reading about a Korean(?) company experimenting with a
public address system that generated a carrier around 20KHz plus an audio
signal shifted up by 20KHz, the assumption being that the non-linearity of
the ear would make it audible. The transducers were placed in a matrix
several feet above head height, and because of beaming at these frequencies
the sound(!) would appear generally from above. But the last I heard was
that they were experimenting with a membrane above the listener to create
additional non-linearity.

Or this: http://www.atcsd.com/tl_hss.html

Kal

"Kalman Rubinson" wrote in message

On Wed, 16 Jul 2003 16:34:34 +0100, "Graham Holloway"
wrote:

I seem to remember reading about a Korean(?) company experimenting
with a public address system that generated a carrier around 20KHz
plus an audio signal shifted up by 20KHz, the assumption being that
the non-linearity of the ear would make it audible. The transducers
were placed in a matrix several feet above head height, and because
of beaming at these frequencies the sound(!) would appear generally
from above. But the last I heard was that they were experimenting
with a membrane above the listener to create additional
non-linearity.

Or this: http://www.atcsd.com/tl_hss.html

Right, except AFAIK this one is based on the nonlinearity of air. That's a
whole 'nuther thing with SPLs to match.

The reference I had in mind is:

Mechanics of the mammalian cochlea
Robles and Ruggero
Physiological Review Vol 81 Number 3 (July 2001) pp 1305 - 52

Thanks Jim,

Steve G found a link for it: (great minds think alike!)

"There's a nice review of this stuff he
http://physrev.physiology.org/cgi/reprint/81/3/1305 (Robles & Rugger
01, Physiol Rev 81: 1305-1352."

Am amazed at the work that's already been done in this area.

In article , íçëéìèî
wrote:

The reference I had in mind is:

Mechanics of the mammalian cochlea Robles and Ruggero Physiological
Review Vol 81 Number 3 (July 2001) pp 1305 - 52

Thanks Jim,

Steve G found a link for it: (great minds think alike!)

"There's a nice review of this stuff he
http://physrev.physiology.org/cgi/reprint/81/3/1305 (Robles & Rugger 01,
Physiol Rev 81: 1305-1352."

Am amazed at the work that's already been done in this area.

FWIW I *have* written an article on this topic for one of the audio mags.
The above paper was one of the main sources I used. Snag is, although it
was accepted for publication, the editor hasn't edited it down and
published it yet!

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html