Treatment should not be louder than a whisper - after all, you're supposed to be sleeping. The noise of the machine may fluctuate between inhalation and exhalation, but should mimic that of a soft breathing sound.
If your equipment is making loud noises, some of the parts might not be connected properly or it may need to be repaired. If you are hearing a hissing noise, check that all your equipment is connected properly and that there are no holes or deformities.
If you are hearing a grinding or whirring noise, please contact us on 1800 737 633 as your machine may need to be sent away for repair.