Musical intervals (7)
I believe the answer is:
octaves
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">musical intervals</span>' is the definition.<br/ ><span class="explanation-format__explanation">(octave is a kind of musical interval)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for octaves that I've seen before include "Musical intervals of eight notes" , "lot of notes" , "Eight-note spans" , "8-note hand spans (mus.)" , "Groups of eight consecutive notes on a scale" .)