RICHARD HEYSER
Time Delay Spectrometry (1967)

Sometimes, even the greatest ideas take a while to come to fruition. In 1967, Richard C. Heyser, a research engineer at the Jet Propulsion Laboratory of the California Institute of Technology published a landmark paper in the AES Journal. Titled "Acoustical Measurements by Time Delay Spectrometry," the article described a technique whereby loudspeakers and other electro-acoustical systems could be measured in a reverberant, real-world space—without requiring an anechoic chamber. Others saw additional applications for TDS, such as measuring room acoustics. Unfortunately, the horsepower  to perform such computations using 1960s technology was simply unavailable, but Heyser's concept of TDS drew wide acceptance.

Later, acoustician/educator offering them licenses to build and operate TDS devices created by combining off the shelf products from GenRad and Tektronics Don Davis organized a seminar with 20 leading audio engineers/researchers, and Cal Tech with a custom Heyser-designed interface.

Finally, TDS went big time in 1983, when Crown's Techron division unveiled the TEF System 10, the first portable TDS analyzer/acoustical measurement system. Encompassing the gamut of TDS measurements, TEF (Time-Energy-Frequency) included energy-time curves and the ability to show complex waterfall displays of audio spectra. The 40-pound suitcase System 10 units included a custom computer with 96 kilobytes of RAM and a 9-inch green-phosphor screen and cost $14,500. However, acoustical research would never be the same, as for the first time, complex on-site measurements of systems and spaces were possible from a commercially-available product.

Richard Heyser's work was not limited to audio—as we know it. During his distinguished career, he contributed to advancements in ultrasound and in underwater/space imaging as well as techiques for mapping earthquake faultlines using sonic waves. He was presented with numerous accolades during his lifetime, and was elected president of the AES, but passed away in 1987 before his term began.