Okay guys, I have a question for any musicians or people who are good at maths (ideally both).
I was trying to figure out a metric modulation in the song Ancient Temperament by Eidola. The first section (approx 2:58 in the video) is in 6/8, and it then goes into a section in 4/4 . However, if you keep tapping the 8th notes from the previous time signature you end up with a 3/2 polyrhythm, which means that there is not only a time sig change but a tempo change. What's more, if you clap that 3/2 polyrhythm through the 4/4 section, you will find that it changes back to 6/8 at the previous tempo (around 3:28), and you're then clapping 8th notes as you were before.
I managed to figure out that if the first section in 6/8 is at 90bpm, then next in 4/4 must be 126bpm. The problem is… I have no idea how I managed to figure that out. I've double checked my maths, and I did the sums wrong, but somehow still ended up blundering into the correct answer.
I can also even tell you that you could play half note triplets in 4/4 at 225bpm and get the same pulse, but again, I have no idea how I managed to figure that out. I've been puzzling over this since just after I figured it out the first time around, and I can't even understand how I came to the conclusions I came to.
How would you go about figuring out this tempo change, /music/?
compound times like 6/8 are actually 2/4 divided by triplets.
By your description you could write down the whole song as 12/8 and have some passages where all the notes are dotted and have passages where a lines plays a rhythm with all the notes dotted against another where all the notes are triplets.
True, but it's more of a feel thing. For instance, the verse is divided up between bars of 5/8, 6/8 and 3/4. The tempo is the same between the bars of 6/8 and 3/4 so there is no polyrhythmic sillyness, but the drum pattern changes so that the snare hits on the "and" (1 and
), so whilst you can count it as 6/8, it's not a very accurate description.
Besides which, I don't think this solution solves for the added tempo change in the section I described.