Circular breathing is a technique used by players of some wind instruments to produce a continuous tone without interruption. This is accomplished by breathing in through the nose while simultaneously pushing air out through the mouth using air stored in the cheeks.
The technique was developed independently by several cultures, and is used for many traditional wind instruments.
In the 13th century, Asian metalsmiths who specialized in gold and silver used circular breathing techniques for crafting various decorative and ornamental items. In crafting such items, craftsmen were required to blow continuously to the flame through a pipe with a needle-like hole, in order to make the hard metal melt or soften. From such necessity, craftsmen mastered a circular-like cycle of breathing, simultaneously inhaling through their nose while blowing without any pauses. The introduction of the circular breathing technique in the art of ancient windplayers was a productive invention in its performing technique. 
It is used extensively in playing the Eastern zurna, the Mongolian limbe, the Sardinian launeddas, the Egyptian arghul, the Australian didgeridoo, as well as many traditional oboes and flutes of Asia and the Middle East. A few jazz and classical wind and brass players also use some form of circular breathing.
Although many professional wind players find circular breathing highly useful, few pieces of European orchestral music composed before the 20th century actually require its use. However, the advent of circular breathing among professional wind players has allowed for the transcription of pieces originally composed for string instruments which would be unperformable on a wind instrument without the aid of circular breathing. A notable example of this phenomenon is "Moto Perpetuo", transcribed for trumpet by Rafael Méndez from the original work for violin by Paganini.
In 1997, a Guinness World Record was set for longest held musical note. Kenny G used circular breathing to sustain an E-flat on a saxophone for 45 minutes and 47 seconds. On February 2000, Vann Burchfield set a new Guinness world record for circular breathing, holding one continuous note for 47 minutes, 6 seconds, surpassing Kenny G’s record.
The musician inhales fully and begins to exhale and blow. When the lungs are nearly empty, the last volume of air is blown into the mouth, and the cheeks are inflated with this air. Then, while still blowing this last bit of air out by squeezing the cheeks, the musician must very quickly fill the lungs by inhaling through the nose prior to running out of the air in the mouth. If done correctly, by the time the air in the mouth is nearly exhausted the musician can begin to exhale from the lungs once more, ready to repeat the process again. Essentially, circular breathing bridges the gap between exhalations. The air stored in the person's cheeks is used as an extra air reserve to play with while they sneak in a breath through their nose.
Instruments with circular breathing integral to technique
Musicians known for circular breathing
- Rahsaan Roland Kirk – jazz multi-instrumentalist
- Harry Carney, baritone saxophonist and clarinetist, prominent member of the Duke Ellington Orchestra
- Sonny Rollins - American jazz musician
- David S. Ware - American jazz musician
- Anthony Braxton - American saxophonist and composer
- Roscoe Mitchell – jazz multi-instrumentalist
- David Murray- Plays tenor saxophone and, on occasion, bass clarinet
- James Carter - American jazz musician
- Theodosii Spassov - Bulgarian kaval performer and composer
- Sharon Bezaly, classical flautist
- Bora Dugic - Serbian flautist and composer[verification needed]
- Martin Fröst - Swedish clarinetist
- Kenny G - American smooth jazz saxophonist
- Daniel Goode – avant-garde clarinetist
- Stephen Kent - didgeridoo
- Irvin Mayfield – Grammy Award-nominated jazz trumpeter, composer and cultural ambassador to New Orleans
- Rafael Méndez - Mexican virtuoso solo trumpeter
- Sergei Nakariakov - classical trumpeter 
- Evan Parker - free improvising saxophonist noted for his lengthy circular breathing excursions on soprano and tenor saxophones
- Ned Rothenberg - multi-instrumentalist
- Eugene Rousseau – classical saxophonist
- Xavier Rudd - modern one-man band
- Colin Stetson- saxophonist and multi-instrumentalist 
- Clark Terry - Jazz trumpet and flugelhorn player and educator. Author of Clark Terry's System of Circular Breathing (1976).
- Trombone Shorty (Troy Andrews) - Trombonist and trumpeter
- Amy Dickson - Saxophonist from Australia 
- Jonah Parzen-Johnson - Baritone Saxophonist and composer.
- Courtney Pine - Jazz Saxophonist e.g. on "Modern Day Jazz Stories" album.
- John Surman - Jazz multiinstrumentalist, mostly on saxes and clarinets, on "Cloud Line Blue" and other albums.
- John Zorn - American avant-garde composer, arranger, producer, saxophonist and multi-instrumentalist.
- Wynton Marsalis – American jazz and classical trumpeter
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Having arranged the piece for saxophone, Amy then had to spend a further 6 months learning how to circular breath (a technique where you can both inhale and exhale air at the same time) in order to actually be able to play it!
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