From an article in the Wall Street Journal:
There’s a 1976 recording of James Galway playing Paganini’s “Moto Perpetuo” on his golden flute, in which you never once hear him draw breath. At the time, it was lauded as an almost superhuman feat; a virtuosic example of circular breathing, a technique that allows wind players to simultaneously inhale air through the nose while breathing it out through the mouth. (Galway later confessed the recording had been spliced together.) In 1997, saxophonist Kenny G used circular breathing to play a continuous, unbroken note for a total of 45 minutes and 47 seconds, earning him a mention in the Guinness Book of Records.The article goes on to discuss how important the breath is to flute players, and how some contemporary flautists are choosing to leave the inhalation audible rather than trying to suppress the sound (video at the link).
Her inhalations, too, became part of the music. Contemporary composers like Fujikura, says Chase, “have started to think of breath as an ornament and as an expressive device in its own right, whether it’s a subtle, moody breath or the dramatic gesture of an inhalation. Some breaths are even notated in the music: it increases the drama.”In the video, Kenny G demonstrates the technique of circular breathing.