Why You Hear What You Hear: An Experiential Approach to Sound, Music, and Psychoacoustics,

Eric J.
Princeton U. Press
Princeton, NJ
, 2013. $99.50 (624 pp.). ISBN 978-0-691-14859-5

There’s a good reason Harvard University’s Eric Heller titled his book Why You Hear What You Hear: An Experiential Approach to Sound, Music, and Psychoacoustics. He hopes the reader will learn from doing. Much of those three areas of acoustics can be experienced via the ears or can be shown in animations, which can often make those topics accessible to students without much math or physics background. Consequently, the book frequently directs readers to its extensive supporting website, http://www.whyyouhearwhatyouhear.com. For several decades now, books on acoustics have been supplemented with sound recordings, and the use of the Web is an important next step. This book’s website contains suggestions on using a variety of readily available software for sound analysis and synthesis and for creating wave-behavior animations. It also links to many other animations and sound media.

Heller’s combined topic order is somewhat unusual. For that reason, Why You Hear What You Hear tells you “how to use this book”: Because of the extensive cross-referencing, readers are encouraged to abandon the traditional linear approach and to navigate to chapters—and also to the website—according to interest and need.

The book grew from a course called The Physics of Music and Sound that Heller taught at Harvard, first as a core curriculum course in physics, and later as a general education course. For nonphysics majors taking music or any of the many other courses that involve sound, this book is a fresh alternative to some other texts. It’s also deeper than most. However, for the nonspecialist audience, depth might not always be an advantage.

The first 15 of the book’s 28 chapters develop the science of acoustics in logical and often novel ways. They’re followed by five chapters on musical instruments and the voice; six on psychoacoustics, with an emphasis on pitch perception and consonance; one on room acoustics; and another on outdoor sound. For some humanities students, the book’s equations and some serious physics discussion may trigger an allergic reaction. However, derivations for equations relating to topics such as the exponential horn or Sabine’s reverberation are often sequestered in colored boxes, an organization that indicates to readers with a distaste for that aspect of physics that they can get by without those sections.

Why You Hear What You Hear also has much to interest physicists and physics students. As with many other excellent acousticians, Heller’s primary specialty is not acoustics—his other research areas include chemical physics, surface waves, and quantum scattering. In general, a good physicist can bring novel insights to a new field and an understanding of the standard approach. This book contains a lot of physical insight, and I think it will be the rare acoustician who does not enjoy reading it. I particularly liked the use of color coding to introduce (with a minimum of math) a graphical algorithm to represent autocorrelation. Also interesting are the author’s diversions into history, including a story in which John William Strutt (Lord Rayleigh) and William Henry Bragg seem to have been mistaken about an echo transposed in pitch.

I enjoy and applaud the book’s experiential approach, although the experimentalist in me would like to have seen more suggestions for experiments that go beyond the computer keyboard. Also, I should declare a bias. Instead of writing a book, I publish educational acoustics material extensively on the Web, precisely because it’s so easy to include sound files and other resources.

The successful integration of the associated website invites the question: Why not an entirely electronic or web-based package? One answer is that some discussions are long and have beautiful, still graphics; those work well as a book chapter. Another reason may be the business model: A pay wall would be unpopular on the Web, but in this case the hard-copy book could possibly subsidize an extensive website. Heller’s experiment deserves to work.

The author specifically addresses musicians in the introduction. Many will read the book: Musicians are often passionate enough to undertake deep study of things related to their art and have usually accepted that excellence requires a significant investment of effort. I think, though, that quite a few sales will also be to people from the other end of the music–physics spectrum and beyond: Acousticians will enjoy its interesting perspectives, and physicists and engineers outside of acoustics will find it an attractive introduction to some important parts of the discipline.