Edgar Villchur

Edgar Marion Villchur (28 May 1917 – 17 October 2011 ) was an American inventor, proposing multi-channel compression to make up for the variable loss of loudness compression (recruitment). Each patient's audiogram, combined with individual testing, would determine a custom gain-map program keyed to the individual person. The multi-channel system was adapted to an individual's hearing losses in specific frequency ranges, providing amplification where needed. Equally important, one band would not "pump" another. For example, the bass would not control the gain in the mid and high frequency bands. More importantly, he used "wide dynamic range compression" (WDRC). Unlike the previous "compression limiting" circuits, which limited loud sounds to a certain level but did nothing to increase the gain for quiet sounds, Villchur's WDRC amplifiers increased gain for softer sounds without excessively amplifying louder sounds.

Rather than apply for a patent, he decided to publish his findings and make them freely available. Fred Waldhauer of Bell Labs heard Villchur lecture on this new hearing aid system, and started a Bell Labs project to develop a hearing aid. Bell Labs assigned a team of experts, including Jont B. Allen, David A. Berkley, Joseph L. Hall and Harry Levitt (City University of NY, Graduate center). Bell Labs developed the first analog circuit, a three-band WDRC, at Allentown PA. This development circuit and effort was then purchased by Rodney Perkins, who created ReSound. Several of the Bell Labs development team from the Holmdel facility went on to work for ReSound, and bought the rights from them for the technology. Based on the AT&T design, and manufactured by AT&T, a programmable hearing aid based on Villchur's principles was marketed under the ReSound label. This effort has been documented in the article by Jont Allen. Over the next twenty-five years, Villchur's innovations became the industry standard for hearing aid design. It is nearly impossible to find a hearing aid today – digital or analog – that does not use multi-channel wide dynamic range compression.

Edgar Villchur has written three books and over one hundred and fifty articles on high fidelity, sound reproduction, audio engineering, and hearing aid technology in both peer-reviewed scientific journals and popular magazines, including two articles written when he was ninety years old. At the 1995 meeting of the Acoustical Society of America he received the Life Achievement Award from the American Auditory Society.

Edgar Villchur died on Monday, October 17, 2011 of natural causes at his Woodstock, New York home, his daughter, Miriam Villchur said. He was 94.

Books by Edgar Villchur