A musical instrument invented by Wilhelm Heckel at the suggestion of Richard Wagner in 1879 and introduced in 1904. 

It is a double reed instrument of the oboe family, but with a wider bore and hence a heavier and more penetrating tone. It is pitched an octave below the oboe and furnished with an additional semitone taking its range down to A. It was intended to provide a broad oboe-like sound in the middle register of the swollen orchestrations of the turn of the 20th century. In the orchestral repertoire it is generally used as the bass of an oboe section incorporating the oboe and the cor anglais, filling the gap between the oboes and bassoons. 

The heckelphone is approximately 1.3 m (4 ft 3 in) in length, and is quite heavy so it is rested on the floor, supported by a short metal peg attached to the underside of its bulbous bell. An alternate second bell, called a 'muting' bell, is also available, which serves to muffle the instrument for playing in a small ensemble. This arrangement is unique among double-reed instruments. It is played with a large double reed that more closely resembles that of a bassoon than that of an oboe.