Hi Mike as you know I've got a mechanical Aortic valve
and with regard to how noisy it is, from personal experience, if you're sitting in a very quiet room someone sitting about a few feet away will be able to here it but I had mine fitted over twenty years ago and have no idea as to how loud the more modern ones are.
As for how annoying they are at times it gets to me but most of the time I hardly notice it(although I suffer from anxiety
attacks so sometimes it worries me) and at other times it's quite reassuring.
I'm getting a Echocardiogram
soon as my doc has referred my to a heart and chest clinic for a yearly check up which will help as I'll know all is well!