Have you ever looked at a piano keyboard and wondered why the notes of an octave were divided up into seven white keys and five black ones? After all, the sounds that lie between one C and another form a continuous range of frequencies. And yet, throughout history and across different cultures, we have consistently divided them into these set of twelve semi-tones.

Now, Deborah Ross and colleagues from DukeUniversity have found the answer. These musical intervals actually reflect the sounds of our own speech, and are hidden in the vowels we use. Musical scales just sound right because they match the frequency ratios that our brains are primed to detect.

When you talk, your larynx produces sound