The Octave tuned harmonica is a cousin of the tremolo harmonica. Note layout is identical but here each reed is doubled by a octave lower tuned note. Both reeds vibrate simultaneously creating the original note + the note one octave lower hence the name Octave harmonica ! Popular models are manufactured by Hohner, Seydel and Suzuki Harmonicaland provides you with a large choice of octave harmonicas ready to be shipped worldwide