New ‘sound absorption’ method cancels out 99.7 percent of all sound

By Kelly Hodgkins Published September 17, 2015

Researchers at Hong Kong University of Science and Technology have discovered a method that allows them to filter out almost all the noise in a given environment — no matter how loud or quiet it is. It’s a near perfect sound absorption system where sound waves come in and don’t come back out.

Most sound removal systems rely on a sound absorption material that absorbs sound waves at a specific wavelength. Different materials that absorb sound at different wavelengths are used in different situations, depending on the sound they are trying to absorb. For complex sound situations, some materials are combined into a composite that can absorb sound at a range of wavelengths, but even this gradient index material has its limitations. It’s not practical to build a multi-layer matrix capable of absorbing all wavelengths of sound. This absorption approach also only dampens the sound as some of the acoustic waves are not absorbed and bounce off the material.

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The Hong Kong University team took a different approach to sound removal, instead of absorbing sound they used a system that cancels out all the acoustic waves in the environment. The system uses a pair of impedance matched resonators that work in tandem to deaden all sound in a room.

The first resonator removes the majority of the incoming sound waves, but even the best resonator is not perfect with some sound waves still scattering back into the room. The second resonator picks up where the first resonator left off. It is tuned to the same frequency as the first resonator, allowing it to use destructive interference to cancel out the small amount of sound that is escaping the first resonator. The system achieves near perfect absorption with the removal of up to 99.7 percent of the sound waves.

This latest research was built upon an earlier study by the group that was published last year in Nature. The group previously used impedance matched resonance to remove sound, but relied on a multi-layer system with a layer of air and a secondary reflective surface. This new system removes the extra layers and achieves near perfect sound absorption in a single layer system.

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Kelly's been writing online for ten years, working at Gizmodo, TUAW, and BGR among others. Living near the White Mountains of…

Cars

Toyota shifts gears: 15 New EVs and a million cars by 2027

Front three quarter view of the 2023 Toyota bZ4X.

After years of cautiously navigating the electric vehicle (EV) market, Toyota is finally ramping up its commitment to fully electric vehicles.
The Japanese automaker, which has long relied on hybrids, is now planning to develop about 15 fully electric models by 2027, up from five currently. These models will include vehicles under the Toyota and Lexus brands, with production expected to reach 1 million units annually by that year, according to a report from Nikkei.
This strategy marks a significant shift for Toyota, which has thus far remained conservative in its approach to electric cars. The company sold just 140,000 EVs globally in 2024—representing less than 2% of its total global sales. Despite this, Toyota is aiming for a much larger presence in the EV market, targeting approximately 35% of its global production to be electric by the end of the decade.
The Nikkei report suggests the company plans to diversify its production footprint beyond Japan and China and expanding into the U.S., Thailand, and Argentina. This would help mitigate the impact of President Donald Trump’s 25% tariffs on all car imports, as well as reduce delivery times. Toyota is also building a battery plant in North Carolina.
For now, Toyota has only two fully electric vehicles on the U.S. market: The bZ4X and the Lexus RZ models. The Japanese automaker is expected to introduce new models like the bZ5X and a potential electric version of the popular Tacoma pickup.
Separately, Toyota and Honda, along with South Korea’s Hyundai, all announced on April 4 that they would not be raising prices, at least over the next couple of months, following the imposition of U.S. tariffs. According to a separate Nikkei report, Toyota’s North American division has told its suppliers that it will absorb the extra costs of parts imported from Mexico and Canada. Another 25% for automotive parts imported to the U.S. is slated to come into effect on May 3.

Cars

Tesla, Warner Bros. dodge some claims in ‘Blade Runner 2049’ lawsuit, copyright battle continues

Tesla Cybercab at night

Tesla and Warner Bros. scored a partial legal victory as a federal judge dismissed several claims in a lawsuit filed by Alcon Entertainment, a production company behind the 2017 sci-fi movie Blade Runner 2049, Reuters reports.
The lawsuit accused the two companies of using imagery from the film to promote Tesla’s autonomous Cybercab vehicle at an event hosted by Tesla CEO Elon Musk at Warner Bros. Discovery (WBD) Studios in Hollywood in October of last year.
U.S. District Judge George Wu indicated he was inclined to dismiss Alcon’s allegations that Tesla and Warner Bros. violated trademark law, according to Reuters. Specifically, the judge said Musk only referenced the original Blade Runner movie at the event, and noted that Tesla and Alcon are not competitors.
"Tesla and Musk are looking to sell cars," Reuters quoted Wu as saying. "Plaintiff is plainly not in that line of business."
Wu also dismissed most of Alcon's claims against Warner Bros., the distributor of the Blade Runner franchise.
However, the judge allowed Alcon to continue its copyright infringement claims against Tesla for its alleged use of AI-generated images mimicking scenes from Blade Runner 2049 without permission.
Alcan says that just hours before the Cybercab event, it had turned down a request from Tesla and WBD to use “an icononic still image” from the movie.
In the lawsuit, Alcon explained its decision by saying that “any prudent brand considering any Tesla partnership has to take Musk’s massively amplified, highly politicized, capricious and arbitrary behavior, which sometimes veers into hate speech, into account.”
Alcon further said it did not want Blade Runner 2049 “to be affiliated with Musk, Tesla, or any Musk company, for all of these reasons.”
But according to Alcon, Tesla went ahead with feeding images from Blade Runner 2049 into an AI image generator to yield a still image that appeared on screen for 10 seconds during the Cybercab event. With the image featured in the background, Musk directly referenced Blade Runner.
Alcon also said that Musk’s reference to Blade Runner 2049 was not a coincidence as the movie features a “strikingly designed, artificially intelligent, fully autonomous car.”

Cars

Audi halts vehicle deliveries to the U.S. as it mulls impact of tariffs

2021 Audi Q5

If you’d been thinking of buying an Audi, now might be the time. The German brand, owned by the Volkswagen Group, has announced it would halt shipments to the U.S. in the wake of President Donald Trump’s 25% tariffs on all imported vehicles.
Audi is currently holding cars that arrived after the tariffs took effect, on April 3, in U.S. ports. But it still has around 37,000 vehicles in its U.S. inventory, which should be able to meet demand for about two months, according to Reuters.
Automakers on average hold enough cars to meet U.S. demand for about three months, according to Cox Automotive.
Audi should be particularly affected by the tariffs: The Q5, its best-selling model in the U.S., is produced in Mexico, while other models, such as the A3, A4, and A6 are produced in Germany.
Holding shipments is obviously a temporary measure to buy time for Audi and parent company Volkswagen. If tariffs stay in place, vehicle prices would likely have to go up accordingly, unless some production is shifted to the U.S. Volkswagen already has a plant in Chattanooga, Tennessee, and is planning a new plant in South Carolina. That latter plant, however, isn’t expected to be operational until 2027 and is currently dedicated to building electric vehicles for VW’s Scout Motors brand.
Other global automakers have also taken drastic measures in response to Trump’s tariffs. Jaguar Land Rover on April 5 said it is pausing shipments of its its UK-made cars to the United States this month. The British sports-luxury vehicle maker noted that the U.S. market accounts for nearly a quarter of its global sales, led by the likes of Range Rover Sports, Defenders, and Jaguar F-PACE.
And on April 3, Nissan, the biggest Japanese vehicle exporter to the United States, announced it will stop taking new U.S. orders for two Mexican-built Infiniti SUVs, the QX50 and QX55.