Pitch perception experiments

The music stops if you don't hit the right spot

New Scientist vol 181 issue 2430 - 17 January 2004, page 13

AFTER well over a century of argument about how our ears and brain
discriminate pitch, one team claims to have made a significant step
towards resolving the debate.

Our ears convert sound waves into vibrations in the basilar membrane
inside a snail-shaped structure called the cochlea. Here hair cells
detect the vibrations and send signals to the brain via the auditory
nerve. One theory is that the brain works out pitch simply from the
timing of signals from nerves, which varies depending on the frequency
of a sound. Models based on this timing theory are currently in vogue.

The competing theory says that perceiving pitch depends on where in the
cochlea nerve signals come from as well as the timing of nerve signals,
based on the fact that different nerve cells detect different
frequencies. The start of the cochlea picks up very high-frequency
sounds, with more distant areas responding best to progressively lower
frequencies.

A clever trick that fools a high-frequency area of the cochlea into
producing low-frequency signals has now been used to test which theory
is correct. The method involves using a high-frequency carrier wave to
stimulate the part of the basilar membrane tuned to such vibrations.
But the wave is broken into tight pulses to make the nerves fire as if
hit by a low-frequency tone, an effect that is supported by as-yet
unpublished experiments.

And in recent experiments with such "transposed tones" some groups have
found that volunteers can determine the direction the tones came from,
even when the carrier frequency is higher than the range within which
we can detect the direction of a sound. This suggests transposed tones
really do trigger nerve signals characteristic of a much lower
frequency. The finding also shows that when it comes to detecting
direction, it does not matter exactly where in the cochlea the signals
originate, says Andrew Oxenham of the Massachusetts Institute of
Technology. But what about determining pitch?

The MIT team asked volunteers to carry out a variety of tasks, such as
determining the higher of two tones or tuning a note to match a
reference tone. With pure tones the subjects performed very well. But
with transposed tones their performance plummeted (Proceedings of the
National Academy of Sciences, DOI: 10.1073/pnas.0306958101). "It was a complete mess," says Oxenham. The results are all the more surprising
given that people say the transposed tones "sound" like low-frequency
ones, albeit with a high buzzy background. "Whatever they're hearing,
the brain doesn't integrate it as pitch at all."

"The beauty of this is how cleanly it establishes that location plays a
role in pitch perception," says Shihab Shamma of the University of
Maryland, College Park. The work does not prove that location is all -
both place and timing may play a role - but it should help focus
attempts to define how the brain discriminates different pitches.

Charles Lucy - lucy@harmonics.com (LucyScaleDevelopments)
------------ Promoting global harmony through LucyTuning -------
for information on LucyTuning go to: http://www.harmonics.com/lucy/
for LucyTuned Lullabies go to http://www.lucytune.com
http://www.lucytune.co.uk or http://www.lullabies.co.uk

Thanks Charles, sounds interesting . . . I only found one article
mentioning it on the web:

http://www.health24.co.za/news/Deafness_Hearing/1-1239,25999.asp

--- In tuning@yahoogroups.com, Charles Lucy <lucy@h...> wrote:
> The music stops if you don't hit the right spot
>
> New Scientist vol 181 issue 2430 - 17 January 2004, page 13
>
>  
>
> AFTER well over a century of argument about how our ears and brain
> discriminate pitch, one team claims to have made a significant step
> towards resolving the debate.
>
> Our ears convert sound waves into vibrations in the basilar
membrane
> inside a snail-shaped structure called the cochlea. Here hair cells
> detect the vibrations and send signals to the brain via the
auditory
> nerve. One theory is that the brain works out pitch simply from the
> timing of signals from nerves, which varies depending on the
frequency
> of a sound. Models based on this timing theory are currently in
vogue.
>
> The competing theory says that perceiving pitch depends on where in
the
> cochlea nerve signals come from as well as the timing of nerve
signals,
> based on the fact that different nerve cells detect different
> frequencies. The start of the cochlea picks up very high-frequency
> sounds, with more distant areas responding best to progressively
lower
> frequencies.
>
> A clever trick that fools a high-frequency area of the cochlea into
> producing low-frequency signals has now been used to test which
theory
> is correct. The method involves using a high-frequency carrier wave
to
> stimulate the part of the basilar membrane tuned to such
vibrations.
> But the wave is broken into tight pulses to make the nerves fire as
if
> hit by a low-frequency tone, an effect that is supported by as-yet
> unpublished experiments.
>
> And in recent experiments with such "transposed tones" some groups
have
> found that volunteers can determine the direction the tones came
from,
> even when the carrier frequency is higher than the range within
which
> we can detect the direction of a sound. This suggests transposed
tones
> really do trigger nerve signals characteristic of a much lower
> frequency. The finding also shows that when it comes to detecting
> direction, it does not matter exactly where in the cochlea the
signals
> originate, says Andrew Oxenham of the Massachusetts Institute of
> Technology. But what about determining pitch?
>
> The MIT team asked volunteers to carry out a variety of tasks, such
as
> determining the higher of two tones or tuning a note to match a
> reference tone. With pure tones the subjects performed very well.
But
> with transposed tones their performance plummeted (Proceedings of
the
> National Academy of Sciences, DOI: 10.1073/pnas.0306958101). "It
was a
> complete mess," says Oxenham. The results are all the more
surprising
> given that people say the transposed tones "sound" like low-
frequency
> ones, albeit with a high buzzy background. "Whatever they're
hearing,
> the brain doesn't integrate it as pitch at all."
>
> "The beauty of this is how cleanly it establishes that location
plays a
> role in pitch perception," says Shihab Shamma of the University of
> Maryland, College Park. The work does not prove that location is
all -
> both place and timing may play a role - but it should help focus
> attempts to define how the brain discriminates different pitches.
>
> Charles Lucy - lucy@h... (LucyScaleDevelopments)
> ------------ Promoting global harmony through LucyTuning -------
> for information on LucyTuning go to: http://www.harmonics.com/lucy/
> for LucyTuned Lullabies go to http://www.lucytune.com
> http://www.lucytune.co.uk or http://www.lullabies.co.uk

--- In tuning@yahoogroups.com, Charles Lucy <lucy@h...> wrote:

/tuning/topicId_52268.html#52268

> The music stops if you don't hit the right spot
>
> New Scientist vol 181 issue 2430 - 17 January 2004, page 13
>
>  
>
> AFTER well over a century of argument about how our ears and brain
> discriminate pitch, one team claims to have made a significant step
> towards resolving the debate.
>

***Looks like the "timing" theory wins over "place" in this set of
experiments. Was that the name of it, "timing...?" I forget, and I
can't find my Brian McLaren at the moment...

J. Pehrson

> -----Urspr�ngliche Nachricht-----
> Von: Joseph Pehrson [mailto:jpehrson@rcn.com]
> Gesendet: Samstag, 7. Februar 2004 16:27
> An: tuning@yahoogroups.com
> Betreff: [tuning] Re: Pitch perception experiments
>

> --- In tuning@yahoogroups.com, Charles Lucy <lucy@h...> wrote:
>
> /tuning/topicId_52268.html#52268
>
>> The music stops if you don't hit the right spot
>>
>> New Scientist vol 181 issue 2430 - 17 January 2004, page 13
>>
>>
>>> AFTER well over a century of argument about how our ears
>>> and brain discriminate pitch, one team claims to have
>>> made a significant step towards resolving the debate.

> ***Looks like the "timing" theory wins over "place" in this
> set of experiments. Was that the name of it, "timing...?"
> I forget, and I can't find my Brian McLaren at the moment...
>
> J. Pehrson

"frequency theory" in contrast to "place theory".......
for most of the explanations how and why we hear, the frequency theory
seems to me much more conclusive.

Werner

>/tuning/topicId_52268.html#52268
>
>> The music stops if you don't hit the right spot
>>
>> New Scientist vol 181 issue 2430 - 17 January 2004, page 13
>>
>>
>>
>> AFTER well over a century of argument about how our ears and brain
>> discriminate pitch, one team claims to have made a significant step
>> towards resolving the debate.
>
>***Looks like the "timing" theory wins over "place" in this set of
>experiments. Was that the name of it, "timing...?" I forget, and I
>can't find my Brian McLaren at the moment...

Actually, the article pitches these experiments as confirming that
place does play a role, in spite of the current vogue of timing
theories.

-Carl

--- In tuning@yahoogroups.com, "Joseph Pehrson" <jpehrson@r...> wrote:
> --- In tuning@yahoogroups.com, Charles Lucy <lucy@h...> wrote:
>
> /tuning/topicId_52268.html#52268
>
> > The music stops if you don't hit the right spot
> >
> > New Scientist vol 181 issue 2430 - 17 January 2004, page 13
> >
> >  
> >
> > AFTER well over a century of argument about how our ears and
brain
> > discriminate pitch, one team claims to have made a significant
step
> > towards resolving the debate.
> >
>
> ***Looks like the "timing" theory wins over "place" in this set of
> experiments. Was that the name of it, "timing...?"

Read it again, Joseph.

--- In tuning@yahoogroups.com, "wallyesterpaulrus" <paul@s...> wrote:

/tuning/topicId_52268.html#52394

> --- In tuning@yahoogroups.com, "Joseph Pehrson" <jpehrson@r...>
wrote:
> > --- In tuning@yahoogroups.com, Charles Lucy <lucy@h...> wrote:
> >
> > /tuning/topicId_52268.html#52268
> >
> > > The music stops if you don't hit the right spot
> > >
> > > New Scientist vol 181 issue 2430 - 17 January 2004, page 13
> > >
> > >  
> > >
> > > AFTER well over a century of argument about how our ears and
> brain
> > > discriminate pitch, one team claims to have made a significant
> step
> > > towards resolving the debate.
> > >
> >
> > ***Looks like the "timing" theory wins over "place" in this set
of
> > experiments. Was that the name of it, "timing...?"
>
> Read it again, Joseph.

***That's a good suggestion, Paul... I read it again carefully and it
got even "weirder" the second time... interesting.

JP