daemon@BARTOK.ENG.SUN.COM (10/12/89)
Music-Research Digest Wed, 11 Oct 89 Volume 4 : Issue 61
Today's Topics:
programs that can infer key/meter (3 msgs)
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Date: 7 Oct 89 15:59:47 GMT
From: "David H. Brown" <gem.mps.ohio-state.edu!uakari.primate.wisc.edu!nic.MR.NET!thor.acc.stolaf.edu!brownd@edu.>
Subject: programs that can infer key/meter
To: music-research@uk.ac.oxford.prg
In article <125936@sun.Eng.Sun.COM> briang@sun.UUCP (Brian Gordon) writes:
>In article <15170@netnews.upenn.edu> hardt@linc.cis.upenn.edu (Dan Hardt) writes:
>>I'd like to know what programs exist that can
>>infer the key and meter of a melody, just based
>>on the pitch and duration information.
>Isn't that what Finale is supposed to do?
Well, yes, this is what everybody thought Finale was supposed to do.
However, I've always had to tell it what key and meter I'm playing in...
even in the transcription mode. Even after it's been told what key a piece is
in, it will sometimes put Ab and F# in the same measure (should be G# and F#)
if these chroma are not part of the key sig.
After playing a piece for transcription and setting the meter,
the tempo is specified by tapping on some MIDI event for each beat while
the computer plays the piece back. This doesn't really feel like the
program is "infering" much of anything.
Even so, Finale is the best program I've ever encountered for handling
complete pieces of music (as opposed to collections of short sequences) in a
comnputer/MIDI environment. It's also so complex that it may well be possible
to get it to infer such things as meter and key, but it probably isn't as easy
as we've all been told.
St. Olaf College has very little to | M M | M M M | M M | M M M | M M |
do with the things I talk about! | M M | M M M | M M | M M M | M M |
| M M | M M M | M M | M M M | M M |
Dave Brown: brownd@thor.acc.stolaf.edu | | | | | | | | | | | | | | | | | |
"I _like_ programming the DX-7!" |_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|_|
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Date: Mon, 9 Oct 89 13:29 BST
From: A.MARSDEN <EJHI4978@UK.AC.QUEENS-BELFAST.CENTRE.VAX1>
Subject: programs that can infer key/meter
To: MUSIC-RESEARCH@UK.AC.OXFORD.PRG
I refer to Brian Gordon's comments in MR-DIGEST v.4 no.58 on an original item
by Dan Hardt on NETNEWS, concerning programs to infer the key and metre of a
melody on pitch and rhythm information alone. This has been precisely the
aim of Prof. Longuet-Higgins and his co-workers at the University of Sussex
(see Longuet-Higgins' book "Mental Processes: Studies in Cognitive Science",
MIT Press 1987). They had a degree of success, but found that there always
remained problematic cases which did not yeild to their system of inference.
If an FRS can work for years on this problem, then I doubt that a commercial
program has overcome all the difficulties. Yes, in many straightforward
cases the key and metre of a melody can be inferred by not-too-complex means,
but many interesting pieces of music are far from straightforward, and some
even apparently deliberately ambiguous. It must be realised that, ultimately,
inferring the key and metre of a piece of music is not a question of pattern
matching, but one of cognitive modelling; it is on a par with parsing
sentences.
Alan Marsden <A.Marsden@uk.ac.qub.v1>
Music Dept., Queen's University, Belfast
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Date: 10 Oct 89 00:27:22 GMT
From: Greg Sandell <mailrus!accuvax.nwu.edu!ferret!sandell@edu.ohio-state.cis.tut>
Subject: programs that can infer key/meter
To: music-research@uk.ac.oxford.prg
>In article <15170@netnews.upenn.edu> hardt@linc.cis.upenn.edu (Dan Hardt) writes:
>>I'd like to know what programs exist that can
>>infer the key and meter of a melody, just based
>>on the pitch and duration information. Does anyone
>>know about programs that can do this?
Now that some responses directly addressing Dan's question have come in, let
me suggest an indirect method. There have been several writings on meter in
music that attempt to list exactly those features which instantiate this or
that time signature. This theoretical material can (and has, I think) become
the basis for something more computational. In particular I am thinking about
A GENERATIVE THEORY OF TONAL MUSIC by Fred Lerdahl and Ray Jackendoff (MIT Press,
1983). Lerdahl (a composer and theorist) and Jackendof (a linguist) use grouping
mechanisms from Gestalt psychology theory to define musical meter. For example,
given a recurring pattern of two beats and silence, where the silence is longer
than the duration of time separating the onsets of the two beats, the second of
the two beats tends to be heard as a strong beat, or, the first beat of a measure.
If the silence is roughly twice as long as the inter-onset time, then 3/4 meter
will be perceived. Of course, competing musical elements could contradict that
and create a different meter, but all things being equal, 3/4 time will be heard.
Of course, real music is more complicated than this simple example, but the book
also describes more complicated conditions
Regarding the ability to figure out the key signature of the piece, I'm sure that
what you are concerned with are non-trivial examples where more than seven
diatonic pitch-classes present. One method uses a rather simple statistical
approach of counting the number of each instance of every pitch-class in the
piece, and comparing it with a prototypical distribution for every possible
major and minor key. This method grew out of the research described
by Carol Krumhansl in "Perceptual Structures for Tonal Music" (MUSIC PERCEPTION 1,
1983, pp. 28-62). (The actual key-finding algorithm has never been published). To
successfully match C major, for example, the count will have to show a tendency to
have more C's than any other note, G's running in second place, E's third, and so on.
I can't remember the exact order of the remaining nine notes, but the remainder of
the 'white notes' follow before any of the 'black notes.' The actual prototypical
distribution is somewhat more detailed that a simple descending distribution
(e.g., the ratio of G's to C's is not identical to that of E's to G's). Despite
the seemingly anti-musical approach of a statistical count, I have seen the
approach work quite well, especially when the pitch classes are weighted according
to their duration and amplitude. Using MIDI, I once used the algorithm to analyze
the keys of real-time performance using exactly that weighting scheme (key velocity
to measure amplitude), and it had pretty good accuracy.
***************************************************************
* Greg Sandell, Institute for Learning Sciences, Evanston, IL *
* sandell@ferret.ils.nwu.edu *
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'Oh Hey, Look at that: there's a fish on a hat;
And we'd like to treat everyone here to a cow souvenir.'
- Peter & Lou Berryman
***************************************************************
* Greg Sandell, Institute for Learning Sciences, Evanston, IL *
* sandell@ferret.ils.nwu.edu *
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End of Music-Research Digest