Why You Hear What You Hear


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The rationale for

Why You Hear What You Hear

The book by Eric J. Heller,

published by Princeton University Press

Why You Hear What You Hear is released! It is available at Amazon.com, Princeton University Press, and other booksellers.

No book about vision or visual art is devoid of diagrams and reproductions, yet books about sound and music are strangely mute. It has been possible to print images in books for centuries, but conveying sound has historically been much more difficult.

Why You Hear What You Hear addresses this problem in three ways. First, the text makes repeated reference to quick ways to generate and analyze sound samples using the Java, MAX, and downloadable application tools used repeatedly in Why You Hear What You Hear, and easily accessible from this web site. Your own variations and experiments are readily accomplished. Second, many premade samples, some by the author and others from around the web, and available on this site. Third, Why You Hear What You Hear ups the ante on visualization tools, including hundreds of color images and diagrams, most of them reproducible using the same applets the author used! Again, variation and experimentation by the reader is straightforward.

Acoustical and psycho-acoustical books, especially non-mathematical treatments, seem particularly rife with descriptions passing for explanations. In contrast, we attempt to explain, relying on graphics, sound, and digital tools to make the science come to life. It is my experience that acoustical phenomena can be fully understood by the nonscientist, but not if terms like resonance, impedance, diffraction, etc. are thrown about carelessly, without clear physical intuition behind them.

Why You Hear What You Hear oscillates in level, and is sometimes conceptually quite advanced. If nothing had evolved in the last 20 years, it would be risky to offer such a book to the non-technical reader. But things have evolved: Anyone with a laptop has a fully portable sound laboratory and recording studio that might have cost hundreds of thousands of dollars not so long ago. Now it is possible to achieve true understanding by showing and doing, at one's own desk or anywhere a personal computer is taken. We seize this new opportunity to actually explain sound to the non-specialist, rather than to present mere descriptions or mnemonics received from on high. There is no doubt this approach sometimes puts more demands on the reader, but the reward is an intuitive understanding previously reserved for sound engineers and acousticians.

In spite of its long history, acoustics is still wide open to discovery. The level of Why You Hear What You Hear is at times only a step away from original research, and we often point out something that needs further investigation. With the approach we take here and the new tools available, readers can experience the sense of discovery that scientists crave. New phenomena or interesting variants on known effects can be exposed using the tools and point of view provided here. You will certainly learn much about your own hearing, including whether it is "normal", and whether you have special abilities or tendencies, such as to listen analytically rather than holistically to complex tones.

The Vibratory Universe is an idea often attributed to mystics. The author is no mystic, but he cannot think of any aspect of the physical universe that is not vibratory at some level. Quantum mechanics teaches us that matter is actually made of waves that have the usual properties of wavelength and frequency; the evidence for this is abundant. Light, microwaves, radio waves, etc. exhibit obvious vibratory wavelike properties. Cosmologists tell us that the whole universe is still vibrating in various modes as a remnant of the Big Bang. Even the most modern and abstruse corner of theoretical physics, string theory, supposes that the different particles found in nature are distinct vibratory modes of tiny string-like objects.

This vibratory universality is another reason for studying sound, the most accessible of all vibrational and wavelike manifestations, for in doing so you are studying the clockwork of the universe. Perhaps this is simply a less poetic way of expressing the idea of music of the spheres, that so captivated Pythagoras and those after him.


A note about software and hardware

Why You Hear What You Hear is designed to be useable without the reader launching applets, recording and analyzing sound, etc. This is made possible in part by the graphical examples peppered throughout Why You Hear What You Hear. That said, it is certain that the experience is deeper and the level of understanding and intuition higher for the reader who interacts with the remarkable tools that have been made available, most of them free (assuming a desktop or laptop computer is at hand).

In the author's opinion, Paul Falstad has published by far the best physics applets anywhere on the web, including many aimed at sound phenomena and wave propagation. I was able to use his beautifully coded Java applets again and again to illustrate the principles of sound production and propagation, knowing that readers can do the same demonstrations themselves, with whatever variations they like. It is easy to set up completely new scenarios, forming the basis for research papers and projects if desired.

Jean-Francois Charles has written several key MAX patches that anyone can experience with the free MAX runtime engine. Easy to use, the patches are nonetheless approaching or reaching research quality when connected to quality microphones, digital-analog converters, and loudspeakers.

Indeed at the high end of the spectrum, approaching research quality results, some expensive microphones and loudspeakers might be required, but the vast majority of interesting investigations can be conducted without expensive equipment, usually just what is onboad a laptop, plus earbuds.

A note about projects.

Projects abound in Why You Hear What You Hear and on this web site, whether they are explicitly stated as such or not. The more or less explicitly spelled out ones on this site carry the red Project: label. Even these, however, should be read even with no intention of actuallyy doing the project, since the wisdom gained is usually still obtainable from the descriptions of the projects.

Far more projects are nascent in chapter pages on this site. For example, in the Chapter 23 page there is a section called: "Add higher frequencies - and drop the pitch". There are many pitch demonstrations presenting themselves as interesting projects. You can do them with Paul Falstad's Fourier, or more flexibly with Jean-Francois Charles' MAX Partials patch for example. This section is not labled with a "Project:" prefix; and an explicit one is not spelled out - because there are so many possible!

Other projects are part of the excercises in the PDF Challenges files on the chapter web pages.

A note about the Auditory Demonstrations CD

A very useful set of auditory demonstrations can be found on the CD "Auditory Demonstrations" by Houtsma, Rossing, and Wagonaars, sold by the Acoustical Society of America (ASA). Nonmembers price: $41.

However the files are avaiable free at this site.

To give you an idea of the utility and history of this disk, the Table of Contents and a short history as found on the ASA website is shown below. Many of the files are mentioned on this website for reference in appropriate chapters, but no files from the CD are stored on this site and no URL's to questionable sites are given.


Table of Contents