CONTENTS 



Chapter Page 



I. SOUND WAVES 



1.1 Introduction 1 



1.2 Sound Waves 2 



1.3 Acoustic Wave Equation 4 



A. Equation of Continuity 4 



B. Equation of Motion 5 



C. Compressibility of a Gas 5 



D. Condensation 6 



E. D'Alembertian Wave Equation 6 



1.4 Plane Waves 7 



A. Particle Velocity in a Plane Wave 9 



B. Pressure in a Plane Wave '. 9 



C. Particle Amplitude in a Plane Wave 9 



1.5 Spherical Waves 10 



A. Pressure in a Spherical Wave 11 



B. Particle Velocity in a Spherical Wave 12 



C. Phase Angle Between the Pressure and the Particle Velocity in a 



Spherical Wave 12 



D. Ratio of the Absolute Magnitudes of the Particle Velocity and the 



Pressure in a Spherical Sound Wave 13 



1.6 Stationary Waves 13 



1.7 Sound Energy Density 14 



1.8 Sound Intensity 14 



1.9 Decibels (Bels) 15 



1.10 Doppler Effect 16 



1.1 1 Refraction and Diffraction 17 



II. ACOUSTICAL RADIATING SYSTEMS 



2.1 Introduction 19 



2.2 Simple Point Source 19 



A. Point Source Radiating into an Infinite Medium SoHd Angle of 47r 



Steradians 19 



B. Point Source Radiating into a Semi-Infinite Medium Solid Angle 



of lir Steradians 20 



C. Point Source Radiating into a Solid Angle of tt Steradians 20 



D. Point Source Radiating into a Solid Angle of 7r/2 Steradians 20 



E. Application of the Simple Source 20 



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