[MEI-L] Beat in 6/8

[Byrd, Donald A.]

Executive summary: In 6/8 specifically, I think it should be a dotted quarter, not an eighth. Now some discussion of the issues:

I think most of us would agree that whether the beat is an 8th or a dotted quarter in 6/8 (or 9/8, 12/8, etc.) depends mostly on the tempo, but I doubt if we want to infer that from metronome marks, much less verbal tempo indications! FWIW, I'd guess the dotted-quarter beat is more common.

Of course the same question arises in compound meters with denominators other than 8. Is the beat in 9/16 a 16th or a dotted 8th? It even worse in irregular meters. In 5/8, a measure might have five beats of an 8th each, or a quarter followed by a dotted quarter, or a dotted quarter followed by a quarter!

But in _Behind Bars_, p. 230, Gould solves the problem in terms of notation with the rule that a single diagonal line means to repeat the previous beamed group of total duration of a quarter (or dotted quarter), two diagonal lines a duration of an 8th (or dotted 8th),  three diagonal lines a duration of… You get the idea. So, while she calls these beat repeats, she defines them in terms of beaming! But of course she's talking about usage for new scores,  not what appears in Weber or Beethoven or whever's manuscripts! 

--Don
  

On Aug 26, 2015, at 2:22 AM, Laurent Pugin <lxpugin at gmail.com> wrote:

> Hi,
> 
> I am looking at beat repeats (<beatRpt>) and I am not sure how to deal with them in 6/8 (or 9/8, etc). Defining the beat in 6/8 is a recurrent issue. Looking at timestamps, it seems that each 8th has to be considered as a beat. But in the beatRpt examples in the guidelines it seems that a 4.th is considered as a beat.
> 
> Considering that the number of slashes have to be encoded in the @rend attribute, rendering the beat repeats properly is not that much of an issue because we could just ignore the beat duration and just display the dashes. (Only rendering repeats of mixed duration values would be an issue since it is not clear how this has to be encoded.) However, this would not work if we need to align them with other voices, for example. Any recommendation on this particular issue (<beatRpt>) and on how to consider beats in 6/8 in general?
> 
> Best,
> Laurent 
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---
Donald Byrd
Woodrow Wilson Indiana Teaching Fellow
Adjunct Associate Professor of Informatics
Visiting Scientist, Research Technologies
Indiana University Bloomington