I see that the concept of “tempo octave” is being used by some researchers in the music information retrieval (MIR) community. This is a confusing term from a musical perspective. Here I explain why this is a bad idea.
Octaves
An octave is a core term in (Western) music theory related to describing intervals, relationships between two notes (and tones!) with a frequency ratio of 2:1. Here is an example of an octave:
The cool thing about an octave is that it serves as the first partial in a harmonic series, an interval in itself, but also a pitch class. The latter allows “moving” chords or melodies up and down without affecting the key of the music being played.
Half-time or double-time tempi
A reason for the confusion with rhythms is that you can also experience similar 2:1 ratios in tempo. For example, if the music is played at 120 BPM, you can clap along at 60 BPM (or 240 BPM). You can also use different meters and note durations in musical scores:
However, the notated meter says nothing about the tempo at which the notes should be played…
Avoid confusion
It is unfortunate to create unnecessary confusion. I have written extensively about how the HCI community began using “gesture” to describe motion and action, confusing both linguists and human movement scientists. The machine learning community has recently embraced the concept of “multimodality”, causing a lot of confusion for those of us working at the intersection of psychology and technology.
It doesn’t make much sense to use terminology that confuses pitch and rhythm. There are some interesting boundary cases between the two when you get into microsound, timbre, texture, and microrhythm. However, that is not under discussion here. If the point is to talk about metric half-time or double-time, or doubling or halving of BPMs, it is better to use terms that are already well-defined in musicology.
Grammarly improved the grammar in this post.