Physical Acoustics: Principles and Methods, Volume l—Part A focuses on high frequency sound waves in gases, liquids, and solids that have been proven as powerful tools in analyzing the molecular, defect, domain wall, and other types of motions. The selection first tackles wave propagation in fluids and normal solids and guided wave propagation in elongated cylinders and plates. Discussions focus on fundamentals of continuum mechanics; small-amplitude waves in a linear viscoelastic medium; representation of oscillations and waves; and special effects associated with guided elastic waves in plates and cylinders. The book also touches on piezoelectric and piezomagnetic materials and their functions in transducers, including polycrystalline ferroelectrics, equations of the piezoelectric medium, and equivalent circuits. The publication takes a look at ultrasonic methods for measuring the mechanical properties of liquids and solids and the use of piezoelectric crystals and mechanical resonators in filters and oscillators. The text then ponders on guided wave ultrasonic delay lines and multiple reflection ultrasonic delay lines, as well as transmission of sound waves in solids, torsional mode delay lines, and transducer considerations. The selection is a valuable reference for readers interested in physical acoustics.