Lots of sensible advice for you to follow. The main thing is to ensure you are not going to be sent huge water bill. Look at the meter and take a reading. Do not use any water and After a few hours check the new reading. If the difference is only slight you probably do not have a big leak on your side although a minor leak could be present. If any leak is substantial the meter would show a noticeable change. Even just a change of 0.1 in an hour is a bad sign. Hope it is just in your ears. I have a steady, continuous hissing in my ears that could be interpreted as an external noise just as you describe. Alistair