So, I am composing another piece that involves time signature switching. I'm starting with the piano solo improvisation that I recorded and I'm thinking of expanding it from solo piano to orchestra. Now, with solo piano, any time signature switch can be justified. But, in an orchestra, I have to take the conductor into consideration. My piece has a lot of emotional development that occurs within it. But there is one emotional development that involves a time signature switch. That is this:
Lamenting(Slow melody with arpeggio bass) -> Dramatic(Fast melody with tremelo bass) -> Lamenting -> Dramatic
The lamenting section doesn't use an actual lament bass progression, but it is very melancholic. I have it at quarter note = 45 BPM and I have it marked Lento lamentoso, literally meaning slow and lamenting. The dramatic section is at quarter note = 160 BPM, for now anyway. I might slow that down a bit, but it is certainly at an Allegro tempo. The Allegro is in 2/4 time. Right now, I have the Lento in 4/4, but I'm wondering if I should have it in 2/2, given that the half note is a very frequent note value and the sixteenths tend to be on the fourth or last eighth of the bar. Both of these suggest a beat of a half note at a tempo of 22.5 BPM.
I do tend to see the half note as the notated tactus in 2 different tempo extremes, the extremely slow and the extremely fast. But it isn't just the tactus making me wonder if I should have the Lento be in 2/2, but also the conducting gestures for 4 beats and 2 beats. I know that conductors could probably get across a 4/4 to 2/4 switch and vice versa just fine by just switching between the 4 beat gesture and the 2 beat gesture. Or could they? Especially combined with the tempo change, I'm worried that if I simply stick with the 4/4, the orchestra will play it as though it is in 2/2 and thus way too fast. Most common duple meter to switch to when combined with a change in tempo that I have seen is 2/2.
If I have the time signature switch between 2/2 and 2/4, the conductor will only have to use 1 conducting pattern throughout the entire piece. Whereas if I have the time signature switch between 4/4 and 2/4, the conductor will have to switch conducting patterns.
For some clarity, here is an excerpt from the Lento Lamentoso section of my piece. I don't have the note values all notated correctly because with this solo piano version, it is more important for me to see the rhythm, thus all the double dotted half notes, even though in an orchestral score in 2/2, those would be better notated as a half note tied to a dotted quarter.
The smaller text within the image are comments related to the motives and what I think would fit in that moment when I write the full orchestral score. I know I'm missing a middle layer. I can only write so much for a solo piano version. I will add that middle layer when I write the orchestral score
So, should I notate the Lento lamentoso section in 2/2 so that the conductor will only have to use 1 pattern and because the sixteenths that occur tend to occur on the fourth and last eighth notes of the bar? Or should I notate it in 4/4 like I have currently and trust that the orchestra won't play the Allegro twice as fast as wanted when the conductor switches from the 4 beat pattern to the 2 beat pattern?