Most people – even those with no formal musical education – are familiar with the term octave, even although they might struggle to define it. This short series of facts might do:

• each note makes the air vibrate at a given speed (frequency) e.g. 440 cycles per second or 440 Hertz (HZ)

• the ear judges pitch by an awareness of the speed of these vibrations

• if the frequency of a note doubles – the pitch goes up an octave (8ve)

• if the frequency of a note halves – the pitch goes down by an 8ve

• this relationship of half/double makes notes fit so well together that upon hearing them simultaneously, many listeners perceive only one note

• for this reason the notes share the same alphabetical name

• moving some of the notes of a melody into a neighbouring 8ve is called 8ve displacement and many composers use it to conjure a sense of strangeness while retaining a sense of the familiar

Octave displacement can seem nearly as odd for the performer as the listener. For most people, it would be easier to do this by reading or memorizing rather than improvising and most would agree that it would be easier on an instrument than with the voice. That’s why this seems so amazing – particularly from 0:29 [kml_flashembed movie="http://www.youtube.com/v/JlJvOCG22aU" width="425" height="350" wmode="transparent" /]