An octave is a unit of measurement used in music to describe the interval between two frequencies. Specifically, an octave is the interval between one musical pitch and another with double its frequency. For example, if one note has a frequency of 440 Hz (the standard pitch for the note A above middle C), the note one octave higher would have a frequency of 880 Hz, and the note one octave lower would have a frequency of 220 Hz.
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