Flexible device could treat hearing loss without batteries

Some people are born with hearing loss, while others acquire it with age, infections or long-term noise exposures. In many instances, the tiny hairs in the inner ear’s cochlea that allow the brain to recognize electrical pulses as sound are damaged. As a step toward an advanced artificial cochlea, researchers in ACS Nano report a conductive membrane, which translated sound waves into matching electrical signals when implanted inside a model ear, without requiring external power.

An electrically conductive membrane implanted inside a model ear simulates cochlear hairs by converting sound waves into electrical pulses; wiring connects the prototype to a device that collects the output current signal.

When the hair cells inside the inner ear stop working, there’s no way to reverse the damage. Currently, treatment is limited to hearing aids or cochlear implants. But these devices require external power sources and can have difficulty amplifying speech correctly so that it’s understood by the user. One possible solution is to simulate healthy cochlear hairs, converting noise into the electrical signals processed by the brain as recognizable sounds. To accomplish this, previous researchers have tried self-powered piezoelectric materials, which become charged when they’re compressed by the pressure that accompanies sound waves, and triboelectric materials, which produce friction and static electricity when moved by these waves. However, the devices aren’t easy to make and don’t produce enough signal across the frequencies involved in human speech. So, Yunming Wang and colleagues from the University of Wuhan wanted a simple way to fabricate a material that used both compression and friction for an acoustic sensing device with high efficiency and sensitivity across a broad range of audio frequencies.

To create a piezo-triboelectric material, the researchers mixed barium titanate nanoparticles coated with silicon dioxide into a conductive polymer, which they dried into a thin, flexible film. Next, they removed the silicon dioxide shells with an alkaline solution. This step left behind a sponge-like membrane with spaces around the nanoparticles, allowing them to jostle around when hit by sound waves. In tests, the researchers showed that contact between the nanoparticles and polymer increased the membrane’s electrical output by 55% compared to the pristine polymer. When they sandwiched the membrane between two thin metal grids, the acoustic sensing device produced a maximum electrical signal at 170 hertz, a frequency within the range of most adult’s voices. Finally, the researchers implanted the device inside a model ear and played a music file. They recorded the electrical output and converted it into a new audio file, which displayed a strong similarity to the original version. The researchers say their self-powered device is sensitive to the wide acoustic range needed to hear most sounds and voices.

Source: https://www.acs.org/

Noise-cancelling Windows Halve Traffic Sounds

People living in cities with warm climates face a problem during summer months: keeping windows open for ventilation means letting in traffic sounds. A noise-cancelling device could solve this dilemma. Bhan Lam at the Nanyang Technological University in Singapore and his colleagues have created a device that can halve the noisiness of urban traffic, reducing the sound coming through an open window by up to 10 decibels.

To cancel out road noise, the researchers used 24 small loudspeakers and fixed these to the security grilles of a typical window in Singapore in an 8×3 grid. These grilles are a common feature across South-East Asia, says Lam. He adds that the spacing of the speakers was dependent on the frequency of the noise that they wanted to cancel out.

The researchers spaced each speaker 12.5 centimetres apart facing outwards and programmed them to emit sounds at the same frequency of noise detected by a sensor placed outside the window. The device was most successful at cancelling noise between frequencies of 300 and 1000 Hz, with up to a 50 per cent reduction in loudness for sounds within this range. It isn’t optimised for the noise from human voices, which have higher frequencies.

The effect is similar to the technology used in noise-cancelling headphones, which are often tuned specifically to cancel out the hum of aircraft engines”, says Lam. “The speakers the team used were only 4.5 centimetres in diameter – too small to cancel out noise at frequencies below 300 Hz. “A speaker needs to move a huge volume of air for low frequency sounds.

The team placed the window in a replica room and played road traffic, train and aircraft noise from another loudspeaker 2 metres away. The frequency of most of the noise from traffic and passing aircraft ranges from 200 to 1000 hertz. Large trucks and motorcycles tend to generate sounds on the lower end of the range, while the majority of the sound from  is around 1000 Hz.

Source: https://www.newscientist.com/

Electric Powered Flight Ten Times Less Expensive

Consumer passenger flight could be the next industry that’s transformed by electric powertrains, and Seattle’s Zunum Aero wants to be at the forefront of that change. The Seattle-based company, which is backed by Boeing’s HorizonX fund and Jet Blue’s Technology Ventures, has a plan to change the fundamental economics of regional flight, and shift the economics of air travel on a path towards eventual fully electric flight.

The first Zunum aircraft is designed for regional service, with seating for 12 passengers and a delivery window starting in 2022. The economics are potentially game-changing, with operating expenses of around $260 per hour for the aircraft. With a max cruise stepped of 340 miles per hour (547 km/h) in the air, a take-off distance of 2,200 feet (671 meters), a total hybrid-electric range of 700 miles (1127 km), which it hopes to scale to over 1,000 (1610 km) )in time and 80 percent lower noise and emissions vs. traditional regional planes, Zunum is position its airplane as the perfect way to light up under-utilized regional airports across the U.S., providing affordable and efficient commuter flights where economic realities have made running regular service impractical.

In the past, very intentionally, we were quiet about operating costs, because it’s just shockingly low what you can get with an electric. So that you can get an aircraft of a size that could never compete with an airliner that can get you below commercial fares,” Zunum Aero CEO Ashish Kumar told in an interview. He put the cost per seat operating expenses at around 8 cents per mile. “That’s about one-tenth the operating cost of a business jet per hour,” he said.

Source: zunun.aero