[MEI-L] Beat in 6/8

Roland, Perry D. (pdr4h) pdr4h at eservices.virginia.edu
Thu Aug 27 16:52:00 CEST 2015

So much ambiguity, so little time to deal with it all.  :-(

It's important to note that the primary goal of an encoding based on notation is to deal with *time signatures*, not meter.  So, while it may offend our musical sensibilities occasionally, treating time signatures literally is the best way to eliminate ambiguity.  All time signatures -- simple, additive (e.g., 3+2/4), and compound -- are treated the same way without regard to context (tempo, date of composition, etc.).  The determination of meter is always contextual.  Even though there are elements named "meter", "meterSig", and "meterSigGrp", so far MEI has not addressed musical meter, only notated time signatures.  Maybe "time", "timeSig", and "timeSigGrp" are better names, but some purists will undoubtedly complain, especially about the use of the name "time".

The term "beat unit" was an attempt to avoid confusion with "musical beats".  Obviously, for the quite/very/terminally literal-minded, it failed.  Perhaps replacing all mentions of "beat" in descriptions and documentation with "beat unit" may help.

I don't think I've ever seen published/printed music in which "inter-measure repetition signs" (how's that for an awful name?) are used for single "beat units" in a compound meter, for example as replacements single 8th notes in 6/8.  What is most often seen is the repetition of half a measure (for example, the 2nd set of three 8th notes in 6/8).  In this case, use the halfmRpt element, not beatRpt.  Doing so avoids the confusion of MEI "beat unit" and "musical beat".

The beatRpt element was intended to allow the encoding of a particular symbol (the dot-slash-dot thing and its relatives), so it's already somewhat of a misnomer since it's not literally about repetition of either MEI "beat units" or "musical beats".  To be absolutely pedantic about it, a beat from the past can never be repeated, only the material that occurred on it.  :-)  So, yes, beatRpt represents the repetition of material that occurred on on previous "musical beat".

What's the problem again?  :-)


Perry Roland
Music Library
University of Virginia
P. O. Box 400175
Charlottesville, VA 22904
434-982-2702 (w)
pdr4h (at) virginia (dot) edu
From: mei-l [mei-l-bounces at lists.uni-paderborn.de] on behalf of Craig Sapp [craigsapp at gmail.com]
Sent: Thursday, August 27, 2015 5:09 AM
To: Music Encoding Initiative
Subject: Re: [MEI-L] Beat in 6/8

Hi Benjamin,

The problem is the ambiguous/conflicting terminology in this sentence:

On 27 August 2015 at 01:19, Benjamin Wolff Bohl <bohl at edirom.de<mailto:bohl at edirom.de>> wrote:
meter.unit contains the number indicating the beat unit, that is, the bottom number of the meter signature.

The problem is that in compound meters such as 6/8
The "musical beat" is a dotted quarter note, while the MEI "beat unit" is an eighth note.  Using the word "beat" in such a way is unfortunate as it can conflict with the musical definition of a beat, and this will continue to cause mis-interpretation of what a beat is.

The duration of a beat is necessary for music analysis, since the treatment of dissonance and consonance is tied to the location of a note on or off of the beat.  The musical beat is also needed to automatically beam notes.  Implicit interpretation of the musical beat can be done with 6/8 by assigning it to be a dotted quarter note, but there are exceptions to this definition which would require a way of assigning an explicit duration to the musical beat.

For example, the middle slow movements in a piano sonata may be labeled as 6/8, with the beat actually assigned to the eighth note, in which case the "musical beat" and the MEI "beat unit" are the same.

Another more common corner case would be time signatures such as 3/8.  Is that a compound meter with one beat in a measure, or a simple meter with three beats in the measure (a variant on a 3/4 meter also possible in slow movements)?

And of course in modern music with irregular meters such as 5/8, the musical beats in the measure may may have two beats as 3+2 eighth notes, or 2+3 or a mixture of both in different measures.

Compound meters resulted in a degeneration of mensural notation.  Since modern rhythms are always "imperfect", to emulate a perfect mensuration dots are added to the notes (which would usually be implicit the mensural metric equivalent).  These are represented as compound meters in modern notation (who knows why they did not invent "2/4." time signatures instead of "6/8" for such cases).  The problem is that modern time signatures are ambiguous, since 6/8 could be considered like C-dot, or it could be considered as a non-compound meter with 6 beat at the eighth-note level.

I whine to Perry every once in a while about this, so we can wait for his reply on how to disambiguate such cases...


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