Basic Concepts of Acoustics

Abstract

As pointed out in the Introduction, the frequency range of ultrasound is defined in a somewhat arbitrary way, at least from the physical point of view. This means that ultrasound is governed by the same physical laws as all other acoustical phenomena. Likewise, the concepts and terms applied in ultrasonics are broadly the same as in general acoustics. Therefore it may be useful to present a short summary of fundamental acoustical ideas and facts in this chapter as far as they are of importance for ultrasonics. With a few exceptions, detailed derivations and proofs are omitted; they can be discovered in any good textbook on acoustics.