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Audibly, this come across as a "big sniff"Â . How common a habit is this? You don't notice yourself doing it at the time, which is typically annoying. Nevertheless, I've heard quite a few close-miked commercial CD recordings with "heavy breathing" of one sort or another on them! Does this make me an artist?
Some recording companies edit extreneous sounds such as heavy breathing, while others, as in the recordings you have mentioned, leave them in.
I once bought a recording of the Bach solo violin sonatas and partitas which had a huge amount of very heavy breathing in. For me, it actually spoilt the recording rather than enhanced it.
As for how to stop the sniffing when you shift, unfortunately there maybe little you can do because although you are aware (from recordings) that you do this, it is otherwise a subconscious action you're unaware of while you are actually playing. You could try and learn to relax your left hand a little more - I know you've mentioned getting tension in your left hand while playing and this might be coming through in your breathing when you are about to make a movement which creates even more physical tension than usual. You may even unwittingly be taking a deep breath and holding it! This would certainly be a sign of some tension in your playing.
It would be worth speaking to someone qualified in Alexander Technique about relaxation and breathing exercises for musicians. Two websites I can recommend are
Alexander Technique in the UK and
this one which is a teacher London W6. In the second one I have specifically linked it to the page where it lists a variety of people and occupations who would benefit.
As for how common this is? Well I don't personally know any colleagues who have heavy breathing problems while playing generally, but in something like a highly emotional solo you might occasionally hear a hint of an intake of breath. Having said that, we've all been through music college and all music colleges have weekly Alexander Technique classes, so maybe that is the key?!
. How common a habit is this? You don't notice yourself doing it at the time, which is typically annoying. Nevertheless, I've heard quite a few close-miked commercial CD recordings with "heavy breathing" of one sort or another on them! Does this make me an artist? 
