Acoustics is a branch of physics that is related to the study of sound. Acoustic waves refer to a type of energy propagation through a medium using adiabatic process. The acoustic waves are characterized using different quantitative parameters such as particle velocity, acoustic intensity, acoustic pressure and particle displacement. A few examples of acoustic waves include seismic waves from an earthquake or volcanic eruption, audible sound from a speaker, and ultrasound used in medical imaging. Ultrasonic waves are a type of sound waves which have a frequency greater than 20 kHz. The human ear cannot hear these sound waves. Ultrasonic waves are widely utilized in non-destructive testing (NDT) and medical diagnosis. The topics included in this book on acoustics and ultrasonic waves are of utmost significance and bound to provide incredible insights to readers. It will also provide interesting topics for research which interested readers can take up. This book aims to equip students and experts with the advanced topics and upcoming concepts in this area of study.