Octave Tuned Harmonicas
Octave tuned harmonicas produce sounds by simultaneous vibration of two reeds in a double hole, tuned one octave apart from each other. The resulting sound is strong and full bodied without a tremolo effect. These harmonicas are specially used for both popular and folk music.
Double harmonicas are two harmonicas built back to back on one body. Each of the two harmonicas of a double harmonica is tuned to separate keys, a fifth apart.