Transposing Instrument

A transposing instrument is a musical instrument whose music is notated at a pitch different from the pitch that actually sounds (concert pitch). Rather than a property of the instrument, the transposition is a convention of music notation—however, instruments whose music is typically notated in this way are called transposing instruments. Playing a written C on a transposing instrument produces a different pitch, and that pitch identifies the interval of transposition when describing the instrument. For example, a written C on a B♭ clarinet sounds a concert B♭. For some instruments (e.g., the piccolo or the double bass), the sounding pitch is still a C, but in a different octave; these instruments are said to transpose "at the octave". Transposing harmoniums or electronic keyboards with a transpose function can also sound a different set of pitches from what is notated, but these are not usually called transposing instruments.