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Re: [Phys-l] Harmonics vs Overtones



A question --

You claim (correctly) that ears have upper limits on what can be heard. I have been told by people in music that although the ear cannot hear above, say 20,000 Hz, the sound will be different if those higher frequencies are there or not. Or, put another way, the trained ear can sense the higher inaudible frequencies being present or not. Anyone have experience, or knowledge in this area?

Oren Quist

________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Dan Crowe [Dan.Crowe@Loudoun.K12.VA.US]
Sent: Wednesday, April 01, 2009 3:25 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] Harmonics vs Overtones

Are the "cross terms", "difference terms", etc. necessary to describe the pressure fluctuations in the air, or do they apply only to the perception of the sound?

I discussed a finite series, only, not an infinite series.

Daniel Crowe
Loudoun County Public Schools
Academy of Science
dan.crowe@loudoun.k12.va.us

curtis osterhoudt flutzpah@yahoo.com> 4/1/2009 4:14 PM >> ( mailto:flutzpah@yahoo.com> )
The problem is that in real instruments, nonlinearities are typically present (there is argument that they make *all* the difference), and so one hears "cross terms", "difference terms", and other bits which are certainly not present in the signal originally used to drive the instruments. The presence of these terms is, of course, dependent on the volume at which the instruments are played, and that's not usually covered by strictly modal decomposition.

As to your question about the possibility of an infinite series forming the sum which is heard:
1) it's possible, so long as the sum is square-integrable (we have to conserve energy, after all);
2) in principle, it doesn't matter, because our ears have upper limits on what they can hear anyway.
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