These include the classical guitar, heckelphone, flugelhorn, cornet, harpsichord, and organ.
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Similar to the bass oboe is the more powerful heckelphone, which has a wider bore and larger tone than the bass oboe.
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Not surprisingly, competent heckelphone players are difficult to find due to the extreme rarity of this particular instrument.
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The addition of the 4 lowest semitones allows it to cover the full intended range of the heckelphone part of Richard Strauss'Eine Alpensinfonie, which descends beyond that instrument's lowest note.
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More examples
An oboe pitched an octave below the ordinary oboe
The Heckelphone (Heckelphon) is a musical instrument invented by Wilhelm Heckel and his sons. Introduced in 1904, it is similar to the cor anglais (English horn).
A double-reed instrument somewhat misleadingly called the baritone oboe; gives out a rich, somewhat hollow sound.