Review published in the International Journal of Acoustics and Vibration, Vol. 14, No. 1, 2009
Acoustics
By: Uno Ingard
This book, written by a distinguished physicist and educator, is a welcome addition to the acoustics community. A total of eleven chapters constitute the book, with the last Chapter exclusively devoted to examples.
Chapter 1 (Introduction) deals with frequency intervals and covers a broad review of various branches of acoustics, which are expanded in separate chapters. Chapter 2 (Oscillations) describes harmonic motion (free and forced) including the damping effects of a linear oscillator, impulse response, and nonlinear oscillators. Chapter 3 (Sound Waves) introduces standing and traveling waves in a fluid medium along with basic definitions (sound speed, intensity, impedance, etc.). Sound propagation in solids is discussed with reference to longitudinal and torsional waves, and concepts such as normal modes, resonance, modal density and flow strength are introduced.
Chapter 4 (Reflection, Absorption, and Transmission) covers the reflection of sound waves at a solid surface, a gaseous interface, and an area discontinuity in a duct. The section on sound absorption includes the mechanisms of sound absorption (including viscous and thermal), resonator absorption, and absorption in porous media. Sound transmission through walls is then examined. Chapter 5 (The Wave Equation) derives the wave equation from the linearized conservation equations. Sources of sound, including monopoles (point source), dipoles (point force), and quadrupoles are presented. Arrays of line sources (strip source) and pistons in an infinite baffle are also discussed. Chapter 6 (Room and Duct Acoustics) begins with reverberation and room acoustics. Then sound radiation in a duct is presented, introducing the concept of wave modes, cut off frequency, and evanescence.
Chapter 7 (Flow-Induced Sound and Instabilities) covers fluid-structure interaction, and flow-induced noise (including turbulence and jet noise). Flow instabilities are also introduced. Chapter 8 (Sound Generated by Fans) treats sound generation by axial fans in a free field with idealized dipoles (point forces) including the effects of nonuniform mean flow. Sound generation by a fan in a duct is then discussed, including rotor-stator interaction. Chapter 9 (Atmospheric Acoustics) discusses sound absorption in the atmosphere due to viscous and thermal conduction effects, and molecular absorption (relaxation), as well as the effects of rain, fog, and snow. Refraction effects due to wind and temperature gradients are reviewed. Chapter 10 (Mean Flow Effects and Nonlinear Acoustics) discusses the effect of mean flow on sound propagation in a duct.
Chapter 11 (Examples) is broken into three sections. Section A (Supplementary Notes) is helpful for understanding the solution of various acoustics problems. The main items included are radiation from circular pistons in infinite walls and ducts, one-dimensional Green’s function applications for ducts with and without mean flow, and sound from an axial fan in a free field.
The book is intended to serve senior undergraduates or firstyear, graduate-level students in a two-semester course. Many early chapters contain basic concepts and phenomena, with greater detail provided in separate chapters. As the author suggests, references are not provided at the end of each chapter although rather general references are provided. The book certainly fulfils the original aim of providing a thorough understanding of the fundamentals of acoustics and serves as a foundation for problem-solving. The many examples in Chapter 11 facilitate this objective. Emphasis is placed on a descriptive presentation to provide physical insight, while keeping the mathematics level and the algebraic steps to a minimum in many cases. A few more figures would have been helpful.
Overall, this book is useful to undergraduate and graduate students, and serves as an important reference for practicing scientists, engineers, and researchers in the field of acoustics. It will be a valuable addition to a library.
Max Kandula
ASRC Aerospace
Kennedy Space Center,
FL 32899 United States