CCRMA Professor Julius Smith’s brilliant on-line text covers just about every topic related to Digital Signal Processing in some form or another. Highly technical and detailed, but also very informative for the non-technical reader.
from the preface…. This book was developed for my course entitled “Signal Processing Methods in Musical Acoustics,” which I have given at the Center for Computer Research in Music and Acoustics (CCRMA) every year since 1984. The course was created primarily as a research preparation and dissemination vehicle intended for graduate students in computer music and engineering interested in efficient computational modeling of musical instruments. Ideally, in addition to a first course in digital signal processing [462,460], the student will also have studied elementary physics, including waves, and a prior first course in acoustics is desirable.