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The ancient aboriginal wind instrument known as a didgeridoo is played with a technique called circular breathing. This provides a continuous sound, and is thought to strengthen the muscles of the upper airway. A 2006 study in the British Medical Journal found that playing the instrument improved sleep apnea.
If you have tried this, please share your experiences in the discussion forum. It may not be for everyone, but if you have given up on CPAP it may be music to your ears.