ISBN-13: 9780123914217, Elsevier Science, 0/4/2012 720PP
I first encountered Leo Beranek’s book Acoustics while researching material for High Performance Loudspeakers which first edition was published in 1976/77, when Acoustics had been in print for some 20 years. Now, more than half a century later and encouraged by Tim Mellow, Beranek and Mellow have collaborated to produce a new edition of Acoustics, founded on the original classical fundamentals but with a modern slant more clearly focused on electroacoustics and carrying the sub-title, Sound Fields and Transducers.
The 2012 edition of Acoustics runs to 704 pages. The first 4 chapters comprehensively deal with acoustical fundamentals, leading to microphone theory and practice in chapter five. Electrodynamic loudspeakers are covered in chapter 6, followed by loudspeaker systems and enclosures in chapter seven. Cell, mobile phone transducer technologies are introduced in chapter eight, leading to a strong chapter nine on horn loudspeakers. This includes an example of a rectangular 7.5cm by 3.9cm treble horn, +/-3dB, 1.5kHz to 10kHz, which provides a typical sound pressure gain of 16dB into a defined radiation angle, a welcome reminder of horn efficiency gains. Chapter ten covers ‘enclosures’, here the design of rooms and halls, followed by a brief look at listening room issues in eleven. From twelve onwards we return to theory where Mellow’s speciality, acoustic radiation and scattering from a variety of theoretical sources in particular situations, comes to the fore.
In chapter twelve the boundary value method is employed while in 13 one can see the contrast with the boundary integral method, here used more comprehensively. These many analyses include some of the issues faced when mounting a high frequency driver on a contoured section of a loudspeaker enclosure. Interesting and relevant examples include the radiation of a spherical cap on a sphere, and radiation from an infinite line source.
In Chapter fourteen, state variable analysis is applied to numerous loudspeaker equivalent circuits, facilitating computation from first principles. Finally, there are some useful appendices, tables, design summaries and conversion factors.
The book is aimed at electroacoustic students and engineers active in transducer and loudspeaker system design. There is an emphasis on understanding the fundamentals, providing sufficient classic example problems for the designer to apply to new product. It won’t tell you how to design a commercial hi fi loudspeaker, but if you have the skills it can explain much of the relevant electroacoustic behaviour from first principles. Designers will find numerous alignment tables, charts, graphs, formulas and worked examples in Chapter 7, for example the complete behaviour of a driven bass reflex enclosure including the higher modes, a useful starting point though understandably not including structural behaviour.
Proficiency in mathematics is a help; this reference work could be regarded as the counterpart to the advanced, computational acoustic engineering software such as Comsol now becoming popular, providing much of the grounding for these multi discipline, coupled modelling programs, while inexpensive math programs such as Mathematica may be deployed to calculate the extensive models supplied in the work
It is a welcome surprise to see Leo Beranek’s Acoustics so exhaustively revised while we also have to thank co author Tim Mellow for his deep commitment to the work.
Technical Editor HIFICRITIC Jan 2013