April 9, 2006, Updated September 14, 2012

‘Noise is one of the worst kinds of environmental pollution,’ says Silentium’s CEO Yossi Barath, “It puts a lot of stress on our brain and has a serious psychological effect, too, not to mention leading to deafness.”

Paddling silently up a river is the sign of a good canoeist. Driving silently across the highway is the sign of a good car manufacturer. Thanks to the Israeli technology of Silentium, automakers such as General Motors will be able to give Americans a quieter ride.

Based in Rehovot, Silentium began working with GM two years ago with a $250,000 R&D agreement. The deal was that if Silentium could silence the air conditioners in GM’s Yukon SUV, the U.S. manufacturing giant would help Silentium get its wheels wet in the American automotive industry.

It worked.

Silentium fitted the GM car with its S-Chip (“S” for silence) technology. The chip studied and predicted what noises the HVAC (for heating, ventilation and air conditioning) would make and sent out wavelengths of the opposite phase, to dampen what would otherwise be heard. General Motors was so impressed by the results that it referred Silentium to Delphi, a GM subsidiary which supplies HVACs and other car parts to the entire automotive industry in the United States.

As part of the agreement, GM will have first rights to install Silentium’s product in GM cars, which is a huge accomplishment in the competitive automotive industry.

“GM was convinced that Silentium offered a good demo,” says Benny Kedar, GM managing director in Israel. “General Motors has connected Silentium with suppliers. That is what is important. There is now a direct link between Silentium and Delphi and I am just waiting to hear the good news.”

Silentium’s CEO, Yossi Barath expects the first prototype on the road by 2008.

“We have demonstrated to General Motors and GM engineers that we can embed our technology into the HVAC system in the car and reduce the noise,” says Barath who agrees that some noise in a car is important for driver safety.

“We are not taking all the noise away,” he told ISRAEL21c. “We give you the ‘sound of silence’, by making the annoying components of noise disappear.”

Curious potential clients, especially European ones, have asked Barath, an engineer, if Silentium could silence the hum of Harley Davidsons. “This is one example,” Barath notes, “where the noise of the machine is important for the driving experience. We wouldn’t want to silence it.”

Silent helmets, quiet airplane cabins and noiseless medical devices are on the company’s agenda for the near future. In the meantime, it is continuing to build products for the computer industry, such as the silent rack mount system (an alternative to space-consuming server rooms in offices), and for the home HVAC market.

A partnership signed last month with a Canadian company, Venmar Ventilation, wholly owned by US-based Nortek, is expected to thrust Silentium into homes and industry around the world.

Venmar, based in Drummondville, Quebec, was looking for ways to quiet its ventilation systems. The company has a unique approach to recycling the warm air lost in return ducts leading outside the home.

“Venmar doesn’t just exchange air, but makes sure all the money invested in warming the air isn’t blown out. People were saying Venmar offered a nice feature and that it kept electricity costs down, but they were complaining that they couldn’t sleep at night because of the noise,” says Barath.

“This match will turbo-charge innovation at our Drummondville plant,” said Daniel Forest, the VP of R&D at Venmar who will work directly with Silentium engineers to tailor products to Venmar’s vents.

“Noise is emitted from everything related to ventilation,” says Barath. “Venmar is mostly domestic, but we think once the products start selling, Nortek in the US will take it to industry as well.”

Ventilation systems present a unique problem in the noise control arena. Both the mechanical parts of the fan and the air running through the ducts make noise. Unlike in some machines where the noise-generating source can simply be insulated, fans and ventilation systems cannot be blocked. Also, the kind of noise emitted from fans is in the lower frequencies (less than 1000 Hz) and not so easy to stop, even with insulation.

According to Barath, noise, whether the pitch is high or low can be heard by the human ear at frequencies of 0 to 20, 000 Hertz (Hz). A little above zero is the lowest or most bass sound we can hear; 20,000 Hz is the highest pitched audible sound. Noise is a type of energy that travels in waves that go on to hit our eardrums which then vibrate according to the length of the wave. Low sounds travel in long wavelengths and high sounds travel in short wavelengths.

Low frequency sounds present a big challenge for companies building mechanical parts. Based on Physics principles, as the sound waves get longer, more insulation is needed to block them. “That’s why, if you have a pub next door you can still hear the bass guitar even after you shut your windows,” says Barath.

‘You can dig a hole deep underground or build walls 10 feet thick but these are not practical solutions to escaping low frequency noise pollution, the kind generated by machinery,” says Barath. “Our technology works best with low frequency noise, which is the most common type of sound emitted by electrical devices. An acoustic sensor is coupled with an output actuator near the noise source.

“Through using algorithms, we have made a large array of microphones that can counteract the sound. This makes us different from other companies out there,” says Barath.

Ever start up your old desktop computer and have it sound like a plane taking off? Or been annoyed by the hum of your neighbor’s air conditioner in the summer months when your windows are open? Noise pollution which emanates from machines and fans is stressful on people. “Noise is one of the worst kinds of environmental pollution,” notes Barath, “It puts a lot of stress on our brain and has a serious psychological effect, too, not to mention leading to deafness.”

The idea for making a sound silencer didn’t come out of thin air. Barath has worked for important Israeli companies; one he has taken to IPO on the NASDAQ. Earlier in his career, he headed the R&D department for the Israel Ministry of Defense where he worked on classified projects. Later, he joined Elbit, a defense and aerospace company. Silentium, which means silence in Latin, was founded in 1997.

Besides working in collaboration with companies such as GM, Intel and Venmar, Silentium plans on taking its own rack mount cabinet (a box providing a quiet and thermally controlled environment for communication) into offices in Boston and New York, where office space is limited; a second product, the ANC Quiet Fan is being marketed to IBM, HP and Sun as a silencer which sits on the back of a server unit to quiet computer noise at the source.

When asked if Silentium’s technology could work on silencing in-laws or noisy neighbors, Barath responds to what he said is an old joke, “If I had a dollar for every time someone asked me that question,” laughs Barath, “I would be a very rich man. In-laws are much more complicated than fans. I could silence my mother-in-law if she had the right spectrum in her voice. But our engineers at Silentium are not magicians. Noise needs to be predictable in order for us to cancel it. I don’t believe you can predict your mother-in-law.”

(See Exclusive video report on Silentium from IsraelHighTech.TV).

More on Innovation

Fighting for Israel's truth

We cover what makes life in Israel so special — it's people. A non-profit organization, ISRAEL21c's team of journalists are committed to telling stories that humanize Israelis and show their positive impact on our world. You can bring these stories to life by making a donation of $6/month. 

Jason Harris

Jason Harris

Executive Director