The Acoustic Suspension Loudspeaker – Part 1

Ed Villchur had many credits to his name.  He actually lived in Woodstock, New York, and for years after the famed concert, had people stopping by his house asking for directions to the Yasgar farm (which wasn’t in Woodstock). When I met Ed, he indeed had long hair much like those who attended the Woodstock concert 15 years earlier.  (I’d had the opportunity to go to Woodstock with my older sister but I blew it off, thinking that it would just be another one of those hot, mosquito infested camping trips that I so despised!) 

Ed was also the inventor of the air suspended (or acoustic suspended) loudspeaker bass speaker or woofer, something we all take for granted today in music and sound reproduction.

I had the honor of hosting Ed Villchur (along with Harry Levitt from CUNY) in the mid-1980s at a conference I sponsored called Seminars on Audition.  These were one day events where the audience was composed of equal parts clinicians, researchers, and hearing aid design engineers.  A strength of these meetings is that participants would learn as much from the person sitting next to them as from the featured speakers. However, when Ed took the podium, it was all Ed.  (Incidentally Harry Levitt was a Bell Labs research engineer when he was asked to help commercialize Ed Villchur’s patent.  It was pure coincidence that I had asked both of these men to be at the same conference at the same time as guest speakers- and both turned out to be very friendly and gracious people.)

Briefly, Ed was a visiting lecturer at MIT in 1954 and he told the story of stopping dead right in the middle of a lecture.  He had been working on creating a series of springs that would connect the speaker diaphragm to the wooden enclosure of the speaker thinking that the springs would offer the ability for the loudspeaker to vibrate optimally in the enclosure.  In the middle of a sentence, Ed realized that the springs could be replaced by the springiness of air, as long as the air was enclosed in a space.

I’m not sure what happened next, but I recall Ed saying that he quickly excused himself, went to his lab, and built the first air suspended loudspeaker, which is now on display in the Smithsonian. It was first commercialized with Henry Kloss and they started up a company called Acoustic Research in Cambridge, MA

I recall back in the 1960s (and perhaps the 1950s, but my memory doesn’t go back quite that far) my parents had these two large box speakers with holes cut into the sides; and then I recall that years later, when I bought my first pair of loudspeakers, they seemed to be much smaller and I couldn’t find any air holes.  That was an “air suspended acoustic loudspeaker”.

In conversations with Ed in the late 1980s and early 1990s, I recall many stories of how physicists and engineers refused to believe what he had accomplished stating that he had violated the laws of physics. Even after the commercial success of the Acoustic Research (AR) loudspeakers, first the AR1 and then the less expensive AR2, scientists refused to believe that they could work.

And, oh yes, did I mention that Ed Villchur invented multi-band compression that is used in hearing aids?

Ed was also the father of multi-band compression and in an old issue of the Journal of the Acoustical Society of America, one can find a plastic 45 record in the back where he demonstrated the potential benefits of this form of non-linear processing.  Of course, back then, his system was analog. This was later taken up by Bell Labs, and several commercializations of this happened in the 1990s.  This is now the standard method of processing speech in the hearing aid industry- unfortunately it’s not the optimal method for music.

The year 1954 was very important for two reasons; it was the year that I was born, and this was about 5 years after the bass reflex speaker was invented….but that would be part 2.

 

 

SHARE THIS!


About Marshall Chasin

Marshall Chasin, AuD, is a clinical and research audiologist who has a special interest in the prevention of hearing loss for musicians, as well as the treatment of those who have hearing loss. I have other special interests such as clarinet and karate, but those may come out in the blog over time.