Take the 2-minute tour ×  Consider the interval D3 G3. This
would form a perfect fourth.  In a sequential interval, say a
quarter note D3 followed by quarter note G3, this still "sounds"
like a perfect fourth so using that interval label seems fine.
However, suppose instead the sequential interval is D3 followed
by G2, thus the second note is lower pitch rather than higher.
Would it be more appropriate to label this interval as perfect
fifth instead of a perfect fourth?  In other words, should an
interval be labelled based on the lowest pitch, regardless of
whether it comes before or after another note in time?
share|improve this question add comment  2 Answers  up vote 5
down vote accepted  The interval label is always going to be
based on the number of half-steps between the two pitches.
Since there are 5 half-steps between D3 and G3, that is a
perfect fourth. Thus, the 7 half-steps between D3 and G2 make it
a perfect fifth.  share|improve this answer @Peter S admittedly,
I thought the same thing you men