Dad's concentrator is very noisy. So much so that my mum has to move it into the kitchen at night for him to sleep. And if you use the phone in the same room, you struggle to hear the other end. The O2 supply company sent an engineer out to check it and although he said it is an 'older' one, the noise level is within the acceptable range and they have no more they could supply. Grrrrrrrrr. My father in law had one and it was soooo quiet and the one we had on holiday earlier this year was completely silent. So are we being picky or do you think it is a valid point?