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Natural Science Forum / Physics / Acoustics / December 2008



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saxophone harmonics

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likesomepassingafternoon@gmail.com - 30 Nov 2008 05:45 GMT
When all the keys are closed on a saxophone, the fundamental produces
the natural harmonic series. As keys open up, and the fundamental
raises in pitch, the overtones get progressively sharper. Why is this?
How does this affect our perception of the tone? Thanks for your help.

D.B.
Jens Rodrigo - 30 Nov 2008 23:09 GMT
> When all the keys are closed on a saxophone, the fundamental produces
> the natural harmonic series. As keys open up, and the fundamental
> raises in pitch, the overtones get progressively sharper. Why is this?
> How does this affect our perception of the tone? Thanks for your help.

Perhaps this can help:

Saxophone Harmonics:
http://www.petethomas.co.uk/saxophone-harmonics.html

Saxophone Harmonics: Hearing with the Ears and the Embouchure:
http://www.wku.edu/~john.cipolla/saxharmonicsWKU.pdf

Saxophone acoustics: an introduction
http://www.phys.unsw.edu.au/jw/saxacoustics.html

JazzLab: Harmonics on tenor sax
http://www.youtube.com/watch?v=wAPoAPfsdpc

Saxophone Harmonics
http://video.google.com/videoplay?docid=6604414214026077986&hl=en

Cheers Jens
likesomepassingafternoon@gmail.com - 01 Dec 2008 03:42 GMT
> likesomepassingaftern...@gmail.com> wrote:
> > When all the keys are closed on a saxophone, the fundamental produces
> > the natural harmonic series. As keys open up, and the fundamental
> > raises in pitch, the overtones get progressively sharper. Why is this?
> > How does this affect our perception of the tone? Thanks for your help.
Thanks for the links although none of them address my original
question. I'll be more specific: I want to know about why some tones
have inharmonic partials, including saxophone in some registers,
clarinet, and strings under high tension and how this affects our
perception of musical tone. Thanks.

D.B.

> Perhaps this can help:
>
[quoted text clipped - 9 lines]
>
> Cheers Jens
Ethan Winer - 01 Dec 2008 13:38 GMT
> I want to know about why some tones have inharmonic partials, including
> saxophone in some registers, clarinet, and strings under high tension and
> how this affects our perception of musical tone.

I know that bells and chimes etc have non-related overtones, but I'll take
your word for it that reeds and strings can do that too. With normal tuning,
guitar strings have only related overtones, but when the strings are old and
stretched, the overtones can be slightly off (a few cents). That is, you
pluck a single string and it sounds out of tune even though it's seemingly
only one note.

As for pitch perception, I'd think that non-related overtones could
possibly make it more difficult to identify the pitch. For example, it can
be tricky trying to identify the pitch of bells and chimes because there are
multiple string unrelated tones all sounding at once.

--Ethan
Helmut Wabnig - 02 Dec 2008 15:57 GMT
>> I want to know about why some tones have inharmonic partials, including
>> saxophone in some registers, clarinet, and strings under high tension and
[quoted text clipped - 13 lines]
>
>--Ethan
Each string or pipe has inharmonic overtones, not only due to
imperfections of the string, but for technical reasons.
Example: piano string. Where does it begin and where does it end?
How precisely can you define the contact point on the stop?
For higher partials the apparent string length is physically shorter
than for the fundamental wave. Same applies to pipes and other
resonance bodies.

w.
Savant - 03 Dec 2008 13:54 GMT
On Nov 30, 9:42 pm, likesomepassingaftern...@gmail.com wrote:
> > > When all the keys are closed on a saxophone, the fundamental produces
> > > the natural harmonic series. As keys open up, and the fundamental
[quoted text clipped - 24 lines]
>
> - Show quoted text -

I'm not an expert of musical acoustics...but I do have a copy of
Olson's "Music, Physics and Engineering." 8-)

According to Olson, the harmonic series for a saxophone is regular.
I.e., tones produced at n*f, n being an odd or even integer. A
saxophone does appear to be unique in that the amplitude variation of
the overtones varies irregularly with the fundamental. However, the
overtones are still n*f.

I think what you might be experiencing - and, again, I'm no expert -
is the natural sharpness that occurs with overtones relative to equal
temperment tuning. Take, for example, the second overtone, which would
be 3*f. Musically, this should be an octave and a fifth above the
fundamental. However, equal temperment dictates that this musical note
should be 2.997*f to be "in tune." Thus, the 3*f overtone that is
heard is perceived as being slightly sharp. As n increases, so will
the degree to which the overtones sound sharp, with the exception of
those that fall on octaves (i.e., 2*f, 4*f, 8*f, etc.).

I believe this relationship would be similar for any musical
instrument that produces n*f overtones, whether n is odd, even, or
both.

HTH.

Savant
Ethan Winer - 03 Dec 2008 16:30 GMT
Savant,

> According to Olson, the harmonic series for a saxophone is regular ... the
> overtones are still n*f.

Yes, I just did an FFT on a few sax samples, and all the overtones were
evenly spaced when viewed on a linear frequency scale. So if there's any
deviation in pitch, it's very minor. Or, more likely, as you described
related to tempering.

--Ethan
Don Pearce - 03 Dec 2008 17:17 GMT
>Savant,
>
[quoted text clipped - 7 lines]
>
>--Ethan

Download a copy of APTuner.

http://www.aptuner.com/cgi-bin/aptuner/apmain.html

It is intended to be a guitar tuner, but when you enable the graph
display you get a moving set of lines of the first five (I think)
overtones plus fundamental. It shows how many cents each is out of
tune, and how they change as the note decays. Fabulous implementation
of an FFT.

d
Signature

Pearce Consulting
http://www.pearce.uk.com

Ethan Winer - 04 Dec 2008 14:29 GMT
> when you enable the graph display you get a moving set of lines of the
> first five (I think) overtones plus fundamental. It shows how many cents
> each is out of tune, and how they change as the note decays. Fabulous
> implementation of an FFT.

Very cool!

--Ethan
Salmon Egg - 03 Dec 2008 18:16 GMT
In article
<f996950c-5b4e-4ee7-97cb-8cb24b7e5ce3@t3g2000yqa.googlegroups.com>,

> According to Olson, the harmonic series for a saxophone is regular.
> I.e., tones produced at n*f, n being an odd or even integer. A
> saxophone does appear to be unique in that the amplitude variation of
> the overtones varies irregularly with the fundamental. However, the
> overtones are still n*f.

This is only approximately true, as it would be for all woodwind
instruments. It is particularly true for saxophones where the closed end
is not as sharply conical as an oboe. The formulas for resonant
frequencies appearing in the American Institute of Physics (AIP)
Handbook take into account the diameters at both ends of the resonator.
Nevertheless, those formulas are also approximations.

Bill

Signature

Private Profit; Public Poop! Avoid collateral windfall!

likesomepassingafternoon@gmail.com - 03 Dec 2008 20:52 GMT
>>I think what you might be experiencing - and, again, I'm no expert -
>>is the natural sharpness that occurs with overtones relative to equal
>>temperment tuning.

Hey folks,

Thanks for taking the time to reply! I understand the relationship
between pure and equal tempered tuning, and this phenomenon is much
different. Saxophone has n*f harmonics only for the lowest three or
four fingerings, then the harmonics go wildly sharp.

Lowest fundamental on tenor saxophone: Ab, 2nd partial: Ab, 3rd
partial: Eb, 4th partial: Ab, 5th partial: C, 6th partial: Eb  etc.
This follows the natural harmonic series:

fundamental tone F (half the keys are open) 2nd partial: F, 3rd
partial: between C and Db, 4th partial: flat Gb, 5th partial: sharp
Bb, 6th partial: Db?

The clarinet only has odd partials, but they go progressively flat,
even when all the keys are closed. e.g.

D fundamental, 3rd partial: A, 5th partial: F, 7th partial: Bb, 9th
partial: D, 11th partial: F.

Clarinetists can practice bugle calls on a Bb major triad off a D
fundamental which boggles my mind.

Any acoustics texts I have read don't discuss this phenomenon at all--
maybe I can record it for you.
Ethan Winer - 04 Dec 2008 14:30 GMT
> maybe I can record it for you.

Or try the AP Tuner Don linked above.
Savant - 04 Dec 2008 16:33 GMT
On Dec 3, 2:52 pm, likesomepassingaftern...@gmail.com wrote:
> >>I think what you might be experiencing - and, again, I'm no expert -
> >>is the natural sharpness that occurs with overtones relative to equal
[quoted text clipped - 26 lines]
> Any acoustics texts I have read don't discuss this phenomenon at all--
> maybe I can record it for you.

If you haven't come across it already, here's a JASA (Journal of the
Acoustical Society of America) article that may be of interest:

"The saxophone spectrum", A. H. Benade and S. J. Lutgen, JASA, Vol.
83, No. 5, May 1988, pp 1900-1907.

In the article, the following was noted: "...slight imperfections in
the air column design may displace (misalign) the resonance
frequencies from the strictly harmonic relationships that are
characteristic of the complete simple cone." This may help explain
what (some of?) you're hearing / observing. (???)

However, FWIW, a visual inspection of the graphs provided in the
article appear to point to fairly regular harmonic relationships for
the tenor (and alto) saxophone, even up past the 10th harmonic. I.e.,
it looks as if displacements, if any, shouldn't normally cause sax
harmonics to be "wildly" sharp or flat.

But, again, I'm no expert. :)

I look forward to any graphs / data you can provide. Also, I would be
curious if you could provide some more detail about your observations
of this. E.g., have you observed it with many different players /
instruments? In many different settings? Always with increasing
sharpness with increasing register? Anything else...???

Thanks,

Savant
Salmon Egg - 03 Dec 2008 06:54 GMT
> > When all the keys are closed on a saxophone, the fundamental produces
> > the natural harmonic series. As keys open up, and the fundamental
[quoted text clipped - 5 lines]
> Saxophone Harmonics:
> http://www.petethomas.co.uk/saxophone-harmonics.html

As in post I mad just before this, I noted that would expect the
saxophone to behave more like a flute as the blown and open end
diameters approached each other. To my tin ear this is demonstrated by
the scale presented in the above link. The timbers at the high end sound
like those of a flute to me.

> Saxophone Harmonics: Hearing with the Ears and the Embouchure:
> http://www.wku.edu/~john.cipolla/saxharmonicsWKU.pdf

Bill

Signature

Private Profit; Public Poop! Avoid collateral windfall!

Salmon Egg - 03 Dec 2008 05:54 GMT
In article
<3d7a38f1-e93c-46fe-b792-bdae196dc29d@i18g2000prf.googlegroups.com>,

> When all the keys are closed on a saxophone, the fundamental produces
> the natural harmonic series. As keys open up, and the fundamental
> raises in pitch, the overtones get progressively sharper. Why is this?
> How does this affect our perception of the tone? Thanks for your help.
>
> D.B.

The saxophone uses a tapered bore. You can imagine a variable instrument
starting with a clarinet that has a uniform bore and varying the taper.
At one extreme, it becomes like an oboe with the reed end becoming the
apex of a cone.

As a clarinet, only odd harmonics of the fundamental get excited. As an
oboe, both odd and even harmonics harmonics are excited. These would be
the same as harmonics of a flute of the same length. The fundamental of
a clarinet of that length would be half the frequency of a flute's
fundamental.

The saxophone falls between the clarinet and the oboe as the taper
changes. Thus, two entirely different harmonic patterns form with the
saxophone in the middle. The relatively large diameter at the reed end
for the saxophone means that you do not get the full effect of a closed
cone end. It should not be surprising that the overtones are going to be
off-pitch to some extent. How closely a saxophone's resonances follow a
flute is determined by the ration of the blown and open end diameters.

If you want to get better numbers, to to the AIP Handbook where the
resonant frequencies of tapered open tubes are calculated. Remember that
the holes in a saxophene my be pushed a bit to give good tuning.

Bill

Signature

Private Profit; Public Poop! Avoid collateral windfall!

ttonon - 09 Dec 2008 03:09 GMT
I think here are a couple important things left out of this
discussion.  One is the difference between sustained, forced
vibration, which reaches steady-state (periodic) motion, and transient
motion.  With strings, and with transient motion, as in the action of
a piano string or a plucked guitar string, the overtones experience
significant departure from a harmonic series, due to stiffness and
other effects mentioned in this thread.  Bells, plates and chimes
behave similarly.  With strings in forced motion, however, as in a
bowed instrument, the stick/slip phenomenon that maintains steady
state occurs principally at the frequency of the fundamental, and of
course must be periodic.  This fact alone requires that all overtones
be precisely some integer multiple of the fundamental.  If such were
not the case, the overtones would very quickly become out of step with
the stick/slip process, as well as with the major string motion.
Noise would result.  A very fine adjustment to this statement, for the
real world, is that there can be very small departures from this rule
only because the overtones have a very small effect on the stick/slip
process.  The same is true with reed instruments, which operate in
forced motion, and let's take beating reeds as an example (e.g.
saxophone).  The beating frequency is that of the fundamental, and all
overtones must thus be precisely some integer multiple of that
frequency, otherwise they would be out of step with the vibration of
the reed, and with the periodic vibration of the air column, and here
as well, the same refinement applies.

A second comment is that, although theoretical solutions for air
column vibration in reed instruments predict, for instance, only odd
harmonics in clarinets, in practice, significant contribution to the
musical tone is made by even harmonics, and I think this is due to
nonlinear effects in coupling the air column vibration with reed
vibration.  This contribution of course is not as pronounced as with
the tapered bores, but it can be observed, as for instance in
Benade's, Fundamentals of Musical Acoustics.

Best regards,
Tom

likesomepassingaftern...@gmail.com wrote:
> When all the keys are closed on a saxophone, the fundamental produces
> the natural harmonic series. As keys open up, and the fundamental
> raises in pitch, the overtones get progressively sharper. Why is this?
> How does this affect our perception of the tone? Thanks for your help.
>
> D.B.
 
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