Walter Meyer wrote:

>Of course Gould wasn't the only artist to accompany himself w/ an audible
>hum.  Serkin did it to, as did Toscanini.

Also:

Ashkenazy (as a conductor), Dutoit, Dorati, and Brendel (especially in the
Schubert sonatas).  Solti used to stomp his feet, creating a loud thump on
some recordings.

I first found Brendel's noises annoying, but eventually got used to them,
and now I kind of like it.

You can really hear Dorati in the last piece of Prokofiev's Scythian Suite
(Mercury recording), in the sunrise part at the end.  He sounds like he's
having a fit.

Another very vocal performer was Frank Miller, the cellist for the CSO
(and the NBC Orchestra, before that -- I think).  He grunted when he
played.  I once had the pleasure of attending a performance by the Chicago
Symphony String Quartet, with him at the cello.  I sat about 15 feet from
him.  He was always making some sort of noise.  For some reason I liked it.
Apparently conductors (including Toscanini) didn't mind it.

Mike