JI in wind ensembles

What actually happens when winds play together in JI, verses
being a some cps off? I'm used to thinking of this in terms of
the sine wave model. Which is, so far as I can see, utterly
inapplicable to this situation.

But thinking back to my trumpet days, it seemed ensembles got
noticeably louder once the chords lock in. Is this caused by
acoustics, or by musicians playing louder once they're sure
of their intonation? Or does it just seem louder? Or hasn't
anyone else had this experience?

And the instrument seems to "buzz". Is it possible the acoustic
energy in the air affects the instruments, in some sort of mode
locking effect?

-Carl

Hello carl
I am amazed at the justness/sweetness that can be achieved by wind
ensemble, especially with single reed instruments. But I do not
think that it is due a physical coupling.

I think it is only the skill of the players that makes JI possible
(more or less like in polyphonic singing). As far as I know,
the fine tuning is made with the lips on single reeds and brasses.
I am not sure for double reeds, flute and recorders, but I think
that the fine tuning is always under the absolute control of the
player.

Bad beginners can easilly miss a simple unison and stay consistentl
out of tune on sustained notes (if you ever heard a class of kids
in their first year of clarinet, you know what I mean). If there
as such thing as a significant physical coupling that would not be
possible.

It may be true that once JI is reach, sound production is more
efficient, but I do not know if they are physically more efficient
(less random destructive interference), psychoacousticaly more
efficient (sound louder) or if it is only an effect feeled by
the player and not really by the audience.

I have some doubt about constructive interference, because even
if we make the hypothesis that perfect phase synchronisation
between instruments can be achieved, phase reinforcement
can increase loudness only if the distance between different
sources is much shorter than wavelength. If distance between
sources is greater, interference is not uniform in space:
depending on the location of the auditor, interference is
constructive or destructive.

For a real world wind ensemble, the critical distance may be
respected if instrument are really close: it may the case for a
fundamental frequency of an unison in mid range: 400-500 Hz ->
wavelength around 75-150cm. For a given distance
between sources, coupling should more and more efficent
as pitch goes down.

But critical distance goes down if we talk about JI interval more
complex than unison. For instance for a JI fifth, critical distance
is 3 time less than for unison, for a fourth, it is 4 time less, major
third 5 time less etc. Physical coupling become less and less likely

Further, the way you experience the coupling is certainly quite
different when you are player/singer than when you are in the
audience. As a choir bass, I experienced the wonderful feeling
of being coupled in a perfect unison with a church organ playing
full-stops. In that case you have the impression to sing louder
because you feel the resonance of the other instrument.
In that case you can get in phase with the organ sound wave at
the location where you vocal tract is: a few meters away (at most),
phase is totally random and the effect diseappears.

I have no idea to substanciate the hypothesis that in tune
nstruments may sound louder for psyhoaccoustic reasons.
But may be I miss something.

In conclusion, as you state, it is probably the assurance effect that
may be the most important one.

yours truly

François Laferrière

--- In tuning@yahoogroups.com, Carl Lumma <ekin@l...> wrote:
> What actually happens when winds play together in JI, verses
> being a some cps off? I'm used to thinking of this in terms of
> the sine wave model. Which is, so far as I can see, utterly
> inapplicable to this situation.
>
> But thinking back to my trumpet days, it seemed ensembles got
> noticeably louder once the chords lock in. Is this caused by
> acoustics, or by musicians playing louder once they're sure
> of their intonation? Or does it just seem louder? Or hasn't
> anyone else had this experience?
>
> And the instrument seems to "buzz". Is it possible the acoustic
> energy in the air affects the instruments, in some sort of mode
> locking effect?
>
> -Carl

Heya Paul, just wanted to call your attention to this, if you
didn't see it, and Francois' reply.

-Carl

>What actually happens when winds play together in JI, verses
>being a some cps off? I'm used to thinking of this in terms of
>the sine wave model. Which is, so far as I can see, utterly
>inapplicable to this situation.
>
>But thinking back to my trumpet days, it seemed ensembles got
>noticeably louder once the chords lock in. Is this caused by
>acoustics, or by musicians playing louder once they're sure
>of their intonation? Or does it just seem louder? Or hasn't
>anyone else had this experience?
>
>And the instrument seems to "buzz". Is it possible the acoustic
>energy in the air affects the instruments, in some sort of mode
>locking effect?

--- In tuning@yahoogroups.com, Carl Lumma <ekin@l...> wrote:
> Heya Paul, just wanted to call your attention to this, if you
> didn't see it, and Francois' reply.

francois' reply was adequate according to my quick scan at the time.
perhaps i need to add to it. i don't see how, even if they are
occupying the same point in space, a set of instrumentalists who
somehow manage to acheive phase-lock (let's say on a unison) could
have enough control to bias in favor of constructive, and against
destructive, interference. the phase relationships will be random,
and thus the total amplitude follows the sqrt(n) law -- the same math
tells you that a random walk with n steps of length 1 will get you an
expected distance of sqrt(n) from the origin. as for loudness, i
guess the fact that many partials are aligned means that the
calculation, going through phons and all that, could give a different
result than when the partials are spread across the spectrum more
evenly. ironically, kraig consistently claims that just intervals are
quieter, the opposite of what you're observing here. he may be right
in that beating has a higher *maximum* loudness than non-beating
(ceteris parebis), so may be more easily audible over large distances
or wherever else there's some loudness threshold that must be
surpassed for the sound to be heard at all, while you may be right in
that wind players may simply play louder when they're feeling this
surety (is that a word?)

> -Carl
>
> >What actually happens when winds play together in JI, verses
> >being a some cps off? I'm used to thinking of this in terms of
> >the sine wave model. Which is, so far as I can see, utterly
> >inapplicable to this situation.
> >
> >But thinking back to my trumpet days, it seemed ensembles got
> >noticeably louder once the chords lock in. Is this caused by
> >acoustics, or by musicians playing louder once they're sure
> >of their intonation? Or does it just seem louder? Or hasn't
> >anyone else had this experience?
> >
> >And the instrument seems to "buzz". Is it possible the acoustic
> >energy in the air affects the instruments, in some sort of mode
> >locking effect?

>francois' reply was adequate according to my quick scan at the time.

Cool, just checking.

>the total amplitude follows the sqrt(n) law

Thanks for bringing this up. I was wondering what the total amp.
would be for random phases.

Harrison, and I'm sure Lucy will chime in here, noticed that clocks in
the same room tend to tick in unison. Bill Sethares once mentioned
'entraining' on this list, re. a comment you made about there being
zero probability that two strings were tuned perfectly in unison (IIRC).
Is it possible that feedback could get the instruments to phase lock
without any extraordinary skill on the part of the performers?

>as for loudness, i guess the fact that many partials are aligned means
>that the calculation, going through phons and all that,

What's phons?

-Carl

--- In tuning@yahoogroups.com, Carl Lumma <ekin@l...> wrote:
> >francois' reply was adequate according to my quick scan at the
time.
>
> Cool, just checking.
>
> >the total amplitude follows the sqrt(n) law
>
> Thanks for bringing this up. I was wondering what the total amp.
> would be for random phases.
>
> Harrison, and I'm sure Lucy will chime in here, noticed that clocks
in
> the same room tend to tick in unison.

if they're big pendulum clocks physically coupled through the wall
they're all mounted on.

> Is it possible that feedback could get the instruments to phase lock
> without any extraordinary skill on the part of the performers?

i'm skeptical, but even if one found some way to do so, i think the
phase relationships would still tend to be random.

> >as for loudness, i guess the fact that many partials are aligned
means
> >that the calculation, going through phons and all that,
>
> What's phons?

search for it on this page:

http://www.psychology.psych.ndsu.nodak.edu/mccourt/website/htdocs/Home
Page/Psy460/Audition%20and%20Vestibular%20Senses/physics%20of%
20sound.html

--- In tuning@yahoogroups.com, "wallyesterpaulrus"
<wallyesterpaulrus@y...> wrote:
> --- In tuning@yahoogroups.com, Carl Lumma <ekin@l...> wrote:
> > >francois' reply was adequate according to my quick scan at the
> time.

Hi Paul, I was, as Carl, nearly surprised that you did'nt enter the
discussion.

> > >the total amplitude follows the sqrt(n) law

That means, for practical purposes, that doubling the number of
a given instrument correspond to a gain of only 1.5 dB. If phase
locking is possible that would be 3.0 dB.

> > the same room tend to tick in unison.
>
> if they're big pendulum clocks physically coupled through the wall
> they're all mounted on.

We are talking about 1Hz frequency, and furthermore, sound waves
propagates much faster in solid than in the air, so, the critical
distance is much greater ( I do no have exact figures at hand, but
I would guess an order of magnitude faster).

That remind me a discussion a few month ago about phase locking in
pipe organ. The idea was more or less dismissed but for the major
thirds (which are only one pipe away due to the symetrical setup of
the pipes). But maybe, coupling of more distant pipes is still
possible
by wave propagation through the wood of the buffet?

If I could have a sound example of pipe organ let say with separate
C, E, G (or equivalent intervals),
then CE, CG EG sustained long enough, that would be sufficient to
check if such coupling exists. If somebody think of such an exemple
in one Bach piece, I would be able to analyse it from a commercial
CD from my collection and check if pitch shift is measureable.

By the way there are astounding exemples of biological phase locking
for low frequencies. There are colony of bioluminescent organism that
"pulse" together on long distance (eg. Biolumiscent insects on a tree,
bioluminescent plancton).

On very low frequency side, a very peculiar long term synchronisation
of hormonal cycles has observed on groups of ewes.

It seems that phase locking is everywhere, given that it is
physically possible to do wrt critical distance.

yours truly

François Laferrière