I thought I would try to simulate some minor variations in pitch by adjusting the pitch of the concerto on some editing software. I increased and decreased the pitch of the piece by increments of 2, 3, and 4 %. I then played the files one after another and listened for the A notes. It is interesting to note how your ear adjusts itself to the slight changes. At around 5% the piece no longer is in A and you can't pick out the A's but up 'til then the A's kind of still sound like A's and still jump out at you.The process of categorical learning remains the same when transferred to musical tones-- you don't learn the concept of A-flat by comparing A-flats to G's, B's, F-sharps, or any of an infinite variety of sounds, and figuring out which properties belong to each; you learn A-flat solely by synthesizing your various experiences of A-flats.
After listening to the files and playing the APA game I went down the road to an appointment. ON my way back a truck horn sounded an A and I thought 'that's A'. It was a low pitched A but was easy to hear and I wasn't even trying to listen for it.
Any way I'm going to continue this type of listening for a while and post my results later.