This book sets out to elaborate on this simple explanation in a most scholarly and comprehensive manner. Harmonic oscillators, linearity and superposition principle, oscillations with one degree of freedom, resonance and sharpness of resonance, quality factor, Doppler effect in sound and light, tape recording, cathodex ray oscillograph, Medical applications of ultrasonic, acoustic intensity and acoustic measurements are some of the important topics which have been given special attention. Although the book is for BSc. (Pass, Honours and Subsidiary) some of the elementary discussions are included to initiate an advanced treatment of the subject. Additional matter on ???What propagates wave motion? Velocity of sound.??? New topics like silence zones, theory of resonator and dependence of the frequency of resonator on the size and shape of the mouth of resonator have been added.