ABSTRACT
The physical phenomenon called 'sound' may be defined as a time-varying disturbance of the density of a fluid medium, which is associated with very small vibrational movements of the fluid particles. In this book, the frequency range of interest is assumed to be the so-called 'audio-frequency' range, which extends from about 20 Hz to 20 kHz. Audio-frequency vibrations can also occur in solid materials, such as steel or wood; these are always accompanied by sound in any fluid with which the solids are in contact. Such solid-borne vibrations may propagate in many different waveforms, unlike sound in fluids. This phenomenon is termed 'structure-borne sound', derived from the more concise German word Korperschall.
