What exactly are you trying to say? The vaccum changed his hearing somehow?
I love Glenn Gould's humming! It most definitely adds to the music. Makes it more human, brings it down-to-Earth.
Im just not sure exactly what you were trying to say, that he said.
Maybe it helped him concentrate on the tactile aspects
Considering Gould’s er… peculiar interpretation of the Mozart Sonatas, it may be a good idea to turn a vacuum cleaner on when listening to them.