One team of Georgia Tech researchers is working to make hearing aids more affordable and accessible. Another is aiming to stem the shortage of PPE by enabling wearers to quickly disinfect face masks and face shields.
Ultra-Low-Cost Hearing Aid Could Address Age-Related Hearing Loss Worldwide
ATLANTA—Using a device that could be built with a dollar’s worth of open-source parts and a 3D-printed case, researchers want to help the hundreds of millions of older people worldwide who can’t afford existing hearing aids to address their age-related hearing loss.
The ultra-low-cost, proof-of-concept device known as LoCHAid is designed to be easily manufactured and repaired in locations where conventional hearing aids are priced beyond the reach of most citizens. The minimalist device is expected to meet most of the World Health Organization’s targets for hearing aids aimed at mild to moderate age-related hearing loss. The prototypes built so far look like wearable music players instead of traditional behind-the-ear hearing aids.
“The challenge we set for ourselves was to build a minimalist hearing aid, determine how good it would be, and ask how useful it would be to the millions of people who could use it,” said M. Saad Bhamla, an assistant professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology. “The need is obvious because conventional hearing aids cost a lot and only a fraction of those who need them have access.”
Details of the project are described in the journal PLOS ONE (September 23).
Age-related hearing loss affects more than 200 million adults over the age of 65 worldwide. Hearing aid adoption remains relatively low, particularly in low- and middle-income countries where fewer than 3 percent of adults use the devices — compared to 20 percent in wealthier countries. Cost is a significant limitation, with the average hearing aid pair costing $4,700 in the United States, and even low-cost personal sound amplification devices — which don’t meet the criteria for sale as hearing aids — priced at hundreds of dollars globally.
Part of the reason for the high cost is that effective hearing aids provide far more than just sound amplification. Hearing loss tends to occur unevenly at different frequencies, so boosting all sound can actually make speech comprehension more difficult. Because decoding speech is so complicated for the human brain, the device must also avoid distorting the sound or adding noise that could hamper the user’s ability to understand.
Bhamla and his team chose to focus on age-related hearing loss because older adults tend to lose hearing at higher frequencies. Focusing on a large group with similar hearing losses simplified the design by narrowing the range of sound frequency amplification needed.
Modern hearing aids use digital signal processors to adjust sound, but these components were too expensive and power hungry for the team’s goal. The team therefore decided to build their device using electronic filters to shape the frequency response, a less expensive approach that was standard on hearing aids before the processors became widely available.
“Taking a standard such as linear gain response and shaping it using filters dramatically reduces the cost and the effort required for programming,” said Soham Sinha, the paper’s first author, who was born in semirural India and is a long-term user of hearing aid technology. “I was born with hearing loss and didn’t get hearing aids until I was in high school,” said Sinha, who worked on the project while a Georgia Tech undergraduate and is now a Ph.D. student at Stanford University. “This project represented for me an opportunity to learn what I could do to help others who may be in the same situation as me but not have the resources to obtain hearing aids.”
The ability to hear makes a critical quality of life difference, especially to older people who may have less access to social relationships, said Vinaya Manchaiah, professor of speech and hearing sciences at Lamar University and another member of the research team.
“Hearing has a direct impact on how we feel and how we behave,” he said. “For older adults, losing the ability to hear can result in a quicker and larger cognitive decline.”
The inexpensive hearing aid developed by Bhamla’s team can obviously not do everything that the more expensive devices can do, an issue Manchaiah compares to “purchasing a basic car versus a luxury car. If you ask most users, a basic car is all you need to be able to get from point a to point b. But in the hearing aid world, not many companies make basic cars.”
For Manchaiah, the issue is whether the prototype device provides sufficient value for the cost. The researchers have extensively studied the electroacoustic performance of their device, but the real test will come in clinical and user trials that will be necessary before it can be certified as a medical device.
“When we talk about hearing aids, even the lowest of technology is quite high in price for people in many parts of the world,” he said. “We may not need to have the best technology or the best device in order to provide value and a good experience in hearing.”
The electronic components of the LoCHAid cost less than a dollar if purchased in bulk, but that doesn’t include assembly or distribution costs. Its relatively large size allows for low-tech assembly and even do-it-yourself production and repair. The prototype uses a 3D-printed case and is powered by common AA or lithium ion coin-cell batteries designed to keep costs as low as possible. With its focus on older adults, the device could be sold online or over the counter, Bhamla said.
“We have shown that it is possible to build a hearing aid for less than the price of a cup of coffee,” he said. “This is a first step, a platform technology, and we’ve shown that low cost doesn’t have to mean low quality.”
Among the device’s drawbacks are its large size, an inability to adjust frequency ranges, and an expected lifetime of just a year and a half. The cost of batteries is often a hidden burden for hearing aid users, and the AA batteries are expected to last up to three weeks, which is still an improvement from the 4-5 day life expectancy of common zinc-air batteries in current hearing aids.
The researchers are now working on a smaller version of the device that will boost the bulk component cost to $7 and require a sophisticated manufacturer to assemble. “We’ll no longer be able to solder them ourselves in the lab,” said Bhamla, whose research focuses on frugal science. “This is a labor of love for us, so we will miss that.”
This story, written by John Toon, was posted to Georgia Tech Research News on September 23, 2020.
Soham Sinha, Urvaksh D. Irani, Vinaya Manchaiah, and M. Saad Bhamla, “LoCHAid: An ultra-low-cost hearing aid for age-related hearing loss.” (PLOS ONE, 2020).
Portable UV Disinfection Chambers Could Help Address PPE Shortage
ATLANTA—Portable disinfection chambers that use ultraviolet (UV) light to inactivate virus particles could allow emergency medical technicians, police officers, healthcare workers, pharmacy technicians, and others to quickly disinfect their personal protective equipment (PPE) as they need it.
Researchers at the Georgia Tech Research Institute (GTRI) have built two prototype chambers to evaluate PPE disinfection using different sources of UV-C light: mercury vapor lamps and light-emitting diodes (LEDs). They used the prototypes to evaluate different power levels and disinfection times with a variety of face shields and face masks used to protect workers from the coronavirus.
“There are tradeoffs in terms of cost, lifetime, and potential heat generated,” said T. Robert Harris, a GTRI research engineer. “We wanted to evaluate these issues so that when others use UV-C for disinfecting PPE, they will have information to make good choices.”
The goal was to provide disinfection chambers as small as possible to allow portability. The chambers were built to accommodate face masks and at least one face shield—a curved sheet of clear plastic that covers the entire face and protects against large droplets that could contain coronavirus. The portability of the chambers could allow them to be used anywhere PPE disinfection is needed.
“We wanted a box that would fit on an ambulance or in a police car so that public service staff who are coming into contact with a lot of people on a regular basis would be able to disinfect their PPE,” Harris said. “This method offers an advantage over chemical disinfection because it doesn’t require drying time or risk of chemical absorption.”
Originally, the project aimed at disinfecting PPE while it was being worn by having healthcare workers walk past an ultraviolet source while going from one hospital room to another. That idea was dropped because the wavelengths needed to inactivate the virus—280 nanometers—can cause skin and eye damage in humans.
For that reason, the prototype portable disinfection chambers include a safety interlock to prevent the door from being opened while the UV light is on. Disinfection takes about eight minutes, depending on the intensity of UV emissions, which vary by the lighting source. The chambers are designed to be cleaned between uses.
“Healthcare workers would put their face masks and face shields into the box, close the lid, and set the timer,” Harris explained. “They would swap out one set of PPE while the other set was being disinfected.”
Ultraviolet light can damage plastic items, but Harris and his colleagues didn’t attempt to evaluate how many disinfection cycles the PPE could withstand. “You would expect UV to ultimately degrade PPE materials in the same way that sunlight slowly degrades polymer materials,” he said.
The research team designed the chambers to provide the level of UV exposure that earlier studies had shown would inactivate the closely related SARs-CoV virus by damaging its outer shell and RNA. The researchers did not attempt to evaluate the ability of the UV light to inactivate the SARS-Cov-2 virus that causes Covid-19.
Other engineering considerations included the need for cooling the UV sources, providing consistent exposure of the PPE to UV light using reflective walls in the chambers, and protecting the mercury vapor lamps from damage during use.
Ultraviolet light is now used in water and wastewater sanitation, food disinfection, killing pathogens in HVAC systems, and other purposes. Because of the growing number of applications, finding enough mercury vapor lamps and LED sources was a challenge for the research program, which was funded by GTRI’s independent research and development program.
Harris hopes the project will encourage others to further develop UV-based portable disinfection systems to supplement other methods for protecting people who encounter the coronavirus.
“This work is part of a realization that multiple tools—including handwashing, surface disinfection, face masks, UV disinfection, social distancing, and other steps—are important and much more powerful when done together,” he said. “We should all use every tool we have at our disposal to combat this virus and really think about things carefully to break every link in the chain of contagious transmission.”
Beyond Harris, the research team included Roger Campbell, Ashton Hattori, Eric Brown, Christopher Hollis, Max Schureck, Howard Atchley, John Stone, Michael Grady, and Benjamin Yang.
This story, written by John Toon, was posted to Georgia Tech Research News on August 10, 2020.