Humming on rare occasion isn't a problem; humming all the way through a work is another matter. It amounts to a re-instrumentation of the work performed. An instrumental work becomes a kind of vocal work. If Gould couldn't help himself, as you suspect, neither can we, in finding his vocal noises an intrusion on a work that requires a respectful silence as much from the musician performing the work as it does from audience members listening to it. How would you feel if someone sitting next to or near you at a concert were to hum along audibly with the music? I suspect it would drive you nuts. I also don't think that making a racket of any kind while performing a work is justified by the performer having been judged outstanding at his profession, by "some" people. Often in listening to recordings, I'll hear various vocal sounds from conductors. Sometimes it's insignificant, at other times it ruins a passage here and there. Perhaps some of these conductors would be less likely to make these noises if they were reminded that these sounds would be heard by posterity in recordings. John P.