How do I interpret two notes in a tempo marking?

Question

Is this the same tempo as (quarter note) = 90, or is it (half note) = 90?

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I know what tempo this is because of the marking next to the bar number, but what does the part below the number mean?

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Is this saying to stay at the same tempo? What does the e mean?

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Edit: In response to the questions, this is "Be Thou My Vision" by David R. Gillingham, published in 2000 by C. Alan Publications. The preview of the score gives the tempo at 16 as (single quarter note) = 90, so that answers my first question.

Going into 54, we are in 3/4 at 76 bpm—marked as (two quarter notes) = 76, but that apparently means the same thing as a single quarter note. So the marking means the same thing as (quarter note) = (dotted quarter note). From these two examples, it would appear I can ignore the smaller notes entirely. I suppose that answers my question of how to interpret the notation, but it raises another question: why did the composer include them?

Answer 1

In reverse order because it seems easier to explain it that way:

The third one probably means that eight notes are to be played as swing eight notes. I.e. where there are two notes in one beat, they are played like a triplet with the first two notes tied, where the first note is twice as long as the second. "E" in Italian means "and" in English solfege. So if there are two eight notes in a beat, e.g. C-D, they are to be played C-and-D. This is done so it's easier to write the notes as plain quarter notes or pairs of eight notes, instead of using dotted quarter notes and triplets.

The second one, I'd have to see the whole score to confirm, but is probably something similar to the above. To simplify things, notes are written as plain quarter notes, but the actual time is quarter + dotted quarter notes.

About the first, I'd say the tempo is half note, and if the time is 6/4 you have 3 beats at 90 BMP in each bar.

Hopefully I didn't miss the mark by too much...

Answer 2

I'm only going to answer the second part of your question; I think MMazzon's explanation to the first part is great.

The [two quarter notes] = [quarter note plus dotted quarter] is simply saying that you need to keep the previous tempo of 3/4 (now feel the pulse in eighth notes) at 76 bpm but that there will be nine, rather than six, of those pulses.

As far as the first question is concerned, it might help if you included a bit of the score so we could see which is more probable, the half or the quarter note = 90. I was thinking the quarter note. If there are long phrases of sixteenth-note runs, it wouldn't be the half note! Or on the contrary, if the movement is much slower, then it probably does mean the quarter note = 90.

Apparently the piece is fairly well-known. Have your figured these questions out now that you have performed it?