Editing Bassoon (section)

===Extended techniques===
Many extended techniques can be performed on the bassoon, such as [[multiphonic]]s, [[flutter-tonguing]], [[circular breathing]], [[tonguing|double tonguing]], and harmonics. In the case of the bassoon, flutter-tonguing may be accomplished by "gargling" in the back of the throat as well as by the conventional method of rolling Rs. Multiphonics on the bassoon are plentiful, and can be achieved by using particular alternative fingerings, but are generally heavily influenced by embouchure position. Also, again using certain fingerings, notes may be produced on the instrument that sound lower pitches than the actual range of the instrument. These notes tend to sound very gravelly and out of tune, but technically sound below the low B{{Music|b}}.

The bassoonist may also produce lower notes than the bottom B{{Music|b}} by extending the length of bell. This can be achieved by inserting a specially made "low A extension" into the bell, but may also be achieved with a small paper or rubber tube or a clarinet/cor anglais bell sitting inside the bassoon bell (although the note may tend sharp). The effect of this is to convert the lower B{{Music|b}} into a lower note, almost always A natural; this broadly lowers the pitch of the instrument (most noticeably in the lower register) and will often accordingly convert the lowest B to B{{Music|b}} (and render the neighbouring C very flat). The idea of using low A was begun by [[Richard Wagner]], who wanted to extend the range of the bassoon. Many passages in his later operas require the low A as well as the B-flat immediately above it; this is possible on a normal bassoon using an extension which also flattens low B to B{{Music|b}}, but all extensions to the bell have significant effects on intonation and sound quality in the bottom register of the instrument, and passages such as this are more often realised with comparative ease by the contrabassoon.

Some bassoons have been specially made to allow bassoonists to realize similar passages. These bassoons are made with a "Wagner bell" which is an extended bell with a key for both the low A and the low B-flat, but they are not widespread; bassoons with Wagner bells suffer similar intonational problems as a bassoon with an ordinary A extension, and a bassoon must be constructed specifically to accommodate one, making the extension option far less complicated. Extending the bassoon's range even lower than the A, though possible, would have even stronger effects on pitch and make the instrument effectively unusable.

Despite the logistic difficulties of the note, Wagner was not the only composer to write the low A. Another composer who has required the bassoon to be [[Diatonic and chromatic|chromatic]] down to low A is [[Gustav Mahler]]. [[Richard Strauss]] also calls for the low A in his opera ''[[Intermezzo (opera)|Intermezzo]]''. Some works have optional low As, as in [[Carl Nielsen]]'s [[Wind Quintet (Nielsen)|Wind Quintet]], op. 43, which includes an optional low A for the final cadence of the work.