Noise

Faculty Book Review

by Eric Mankin

We often call the era we live in the "information age," but it could equally well be called the "age of noise." This is the premise of a stimulating new book by Viterbi School polymath Bart Kosko, a professor of electrical engineering who recently added a law degree to existing credentials in philosophy, economics, mathematics and of course, electrical engineering.

Kosko's look at what Ambrose Bierce called "undomesticated music; a stench in the ear, the chief product and authenticating sign of civilization," illustrates just how far reaching the issue of noise is. He finds paradoxes in noise. He even finds the good side of noise; indeed, he speculates noise may have been the energy that started evolution.

Kosko opens by serving an eloquent guide to the epochally important work by Claude Shannon in defining information in his classic 1948 paper, "A mathematical theory of communication," which involves a rigorous rethinking of the definition of noise into an 'unwanted signal." What had been a general and open-ended term for unwelcome sound suddenly became a precisely formulated concept that could be quantified, analyzed and understood.

With this as the background, all kinds of other familiar problems of modern life pop into unexpected focus. "Your signal is my noise" becomes a continuing thread in the discussion. Kosko examines what can (and can't) be done about noise under the legal system, how too much noise can damage hearing and even health in a text full of striking examples. (Perhaps the most striking: an estimate that a single motorcyclist with a faulty muffler can wake up 200,000 people in a single late night ride through Paris). A wonderful sidetrack explores the wartime work of Hedy Lamarr in patenting 'frequency hopping,' a way of sending signals that sounded like noise to listening enemies.

Kosko also covers the subject he has been researching: the beneficial or useful effects of noise. An intriguing chapter visits "stochastic resonance," a paradoxical effect in which background noise functions as an energy source that some systems can use to power the reception of messages, an effect that Kosko speculates may have been instrumental in the development of life: "biochemical evolution appears to have adapted to the constant assault of thermal noise by using it to build motive structures."

Noise is great accompaniment to a quiet afternoon