Sharp intakes of breath seem to be endemic among some pianists - you can often hear it in recordings by e.g., Pollini (who comes close to grunting at times....) and Brendel (who also hums occasionally, unfortunately, always out of tune). Pollini's grunting is audible in the concert hall too. I've never been to a Brendel recital to know whether his humming is of Gouldian proportions......
I've heard both Brendel and Pollini live many times and never heard any humming or grunting. Of course, in Carnegie Hall even if one is sitting in the 10th row of the orchestra any extraneous sounds from the pianist might dissipate in the large space. Recordings might catch things that no one can hear in a live concert.
In London's 2500-seat Royal Festival Hall, which is the only venue Pollini plays in London these days (except when he takes part in all-Nono chamber concerts, which don't attract huge audiences), he allows the organisers to put on 'students' platform seats' on the left of the piano, which are sold to young people for about $10. (Normal seat prices range from $15 to $80). His solo concerts are always sold out, so boosting the capacity to some 3000 with the addition of the students' and choir seats no doubt helps to pay for the transportation of his own personal concert grand (a Hamburg Steinway-Fabbrini).
The front students' seats are as close as 10 feet away from him, so the lucky students who get seats on the keyboard side have a pretty close-up view of his hands and feet - and also get all the sound effects
. I was never young enough to qualify as a 'student' (even when I was young
), but I usually buy the next cheapest tickets, for the choir seats on the raised tier behind the students' seats, where I get an even better view of his hands from my higher position slightly further away. But not far away enough not to hear his periodic sharp intakes of breath and grunting when he is in full cry......
