Re: Pitch & fundamental frequency


Subject: Re: Pitch & fundamental frequency
From: Kevin Austin (kevin.austin@videotron.ca)
Date: Tue Sep 06 2005 - 20:58:49 EDT


>Selon Greg Eustace <g_eustac@alcor.concordia.ca>:
>
> > I have heard of cases where the pitch of a pitched sound is not
>characterized by the fundamental frequency.

Pitch is psychoacoustic and frequency is physics. Many things effect
pitch, including spectrum and amplitude (and see below).

In a number of natural systems, the 'fundamental' is not a stable
frequency, but the 'pitch' is not perceived as shifting. I think of
the "loose tensioned" string instruments, including harpsichord,
theorbo, lutes, chin and zheng, zithers, sitars ... (*)

Singers will also have a vibrato, but for many people there is still
a(n) independent sense of pitch (stability).

Possibly the 'counterintuitive' nature is part of the shift from
;naive' to sophisticated listening. Fundamental frequency is an
important aspect, but not the only one.

> To reiterate, I am concerned only with those sounds having a
>discernable pitch which is not in obvious one-to-one correspondence
>with the fundamental. Can anyone elaborate on this, as it seems
>counterintuitive to me? It is quite possible that I misunderstood
>the statement being made.

(*) Consider the 'simple' case of the guitar string that when plucked
... the tension increases due to stretching. The tension increase
will raise the fundamental, and the lengthened string will lower the
fundamental. Also the pivot points are not hinged but have rigidity
which displaces the 'harmonic' (sic) partials.

There are other 'intuitive' things in acoustics which are incorrect.
The most blatant being that brass instruments produce the harmonic
series. Brass instruments are pipes stopped at one end, and therefore
produce the odd-numbered partials (.5, 1.5, 2.5, 3.5 = 1, 3, 5, 7
...). But don't try to convince a regular Bavarian band trumpet
player, it's counterintuitive.

Best

Kevin



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