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From: alves@aludra.usc.edu (William Alves)
Newsgroups: comp.music
Subject: Re: New tunings
Keywords: Intonation systems, octaves, tuning systems
Message-ID: <6583@merlin.usc.edu>
Date: 20 Nov 89 01:01:27 GMT
References: <various> <3068@husc6.harvard.edu> <6335@merlin.usc.edu> <3113@husc6.harvard.edu> <6460@merlin.usc.edu> <3194@husc6.harvard.edu> <6540@merlin.usc.edu> <1989Nov19.012518.23314@agate.berkeley.edu>
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Reply-To: alves@aludra.usc.edu (Bill Alves)
Organization: University of Southern California, Los Angeles, CA
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In article <1989Nov19.012518.23314@agate.berkeley.edu> ladasky@codon4.berkeley.edu.UUCP (John Ladasky) writes:
>	I'm taking a psychoacoustics and comuter music class from Dave Wessel
>here at U.C. Berkeley (Dave is formerly of IRCAM).  My notes from the class
>indicate that the 29th harmonic of a typical piano has a frequency 30 times
>that of the first harmonic.  He didn't say what string this was, but I would 
>assume that it was a bass string, since the bass strings, so I've been told,
>exhibit more inharmonicity.  

That would make the inharmonicity about 3%, within the range of my system to
detect, but I must admit, I have never tried to measure a piano's inharmonicity
systematically. Another disclaimer I should have added is that my and most 
spectral displays are not of much use looking at very low amplitude partials 
(such as those very high harmonics where the inharmonicity would become signi-
ficant) because they get lost in the inherent noise and the amplitude resolu-
tion of the system. However, they are still important to the timbre. My intui-
tive statement that virtually all of the spectra of non-percussion instruments
are harmonic (or very nearly so) is still meaningful, I think, especially in 
the context of the discussion on how they might influence tuning systems.

>BTW, I'm pretty sure that the spectra of the
>vibraphone and marimba have a lot of interesting inharmonic activity in the
>attack.

Absolutely! In fact, one long known principal of psychoacoustics is that 
attacks are crucial to our timbre perception. However, one interesting study
which I believe originated from CCRMA (maybe someone could point me to the
exact reference) found that the exact nature of the inharmonics in the attack
were not important; it was their overall amplitude and duration that made a
difference to the timbre. Incidentally, an interesting thing that I discovered
in my own work is that bowing a vibraphone does not give you the timbre of
a struck vibraphone without the attack. If it did, the timbre certainly would
not be very interesting. Instead the scraping of the bow creates very high and
ethereal inharmonic partials which give it its distinctive timbre.

Bill Alves
USC School of Music / Center for Scholarly Technology