Subharmonic

A subharmonic is a component of a periodic wave which has a frequency lower than the declared fundamental. As an example, a component with half the frequency of the fundamental would be the second subharmonic, and whereas the harmonic series are defined by the arithmetic multiplication of the fundamental frequency, subharmonics involve the arithmetic division of the fundamental frequency. Subharmonics can be generated by using special playing techniques in a few musical instruments (such as overblowing on some wind instruments), but are more often created artificially, if required.