I realise this is an old post, so this is mostly for other people who may stumble upon this thread whilst researching.
It is my understanding that the ozone should be going through a humidifier (bubbler) before reaching your ears. This should somewhat reduce the noise. Perhaps more so if you use a diffuser in the bubbler. You would, however, need to experiment.
I have the EXT-120 and there is certainly some high pitch hum that comes through, even with the bubbler. The machine itself is so noisy I am going to create a semi-soundproof box for it. As for the noise whilst doing ear insufflation, the bubbles help to make it sound more pleasing.