The recommendations given thus far are probably good choices for the original question. For those who really want to study *instruments*, I believe that the foremost text is: The Physics of Musical Instruments 2ed. (ISBN 0-387-98374-0), by Fletcher and Rossing. Some may say this is too technical; I say it's not technical enough, but merely an introduction. It does require some understanding of physics at the Halliday & Resnick level, introductory physics with calculus. (Oh, I keep forgetting that they added some guy named Walker.) Fletcher and/or Rossing have also published other books and articles that some readers may find more suitable.
