Each semitone is equal to one twelfth of an octave. There are many types of harmonica, including diatonic, chromatic, tremolo, octave, orchestral, and bass versions. This scheme applies to intervals up to an octave (12 semitones). Roger Taylor tops the final chord with a falsetto B in the fifth octave (B5). Mars possesses a three octave tenor vocal range. Compound intervals are intervals larger than an octave. Moog designed his synthesizer around a standard of one volt per octave. Recorders are either untransposed or in some cases transposed at the octave. The pattern repeats at the interval of an octave. A scale has an interval of repetition, normally the octave. The countersubject is written in invertible counterpoint at the octave or fifteenth. Spears's vocal range spans over one octave from E to C. The English theorbo had just the first string at the lower octave (Thomas Mace). Or Uriah Heep, with vocals revved up an octave. There are bindings in Python, Java and MATLAB/OCTAVE.