Low-cost earplugs help newborns with hearing screening

Newborns across the United States are screened
for hearing loss.
This test is important because it helps families better understand their child's health, but in other countries, it is often not available to children due to the high cost of screening equipment
.

A team led by researchers at the University of Washington has invented a new hearing screening system that uses smartphones and low-cost earplugs instead
.
The team tested 114 patients, including 52 6-month-old babies
.
The researchers also tested the device
on children with known hearing loss.
Their tools performed just as well as commercial devices, which correctly identified all hearing loss patients
.

The team released Oct.
31 in Nature Biomedical Engineering
.

"There are huge health inequalities
in the world.
I grew up in a country without hearing screening, in part because the screening equipment itself is very expensive," said senior author Shyam Gollakota, a professor
at the Paul G.
Allen School of Computer Science and Engineering at the University of Washington.
"The project here is to make newborn hearing screening accessible to all without sacrificing quality
, using the ubiquitous mobile devices that people around the world already have—smartphones and $2 to $3 earbuds.
"

Because babies can't tell doctors whether they can hear a given sound, these tests rely on the mechanics
of the ear.

"When external sounds are played, the hair cells in the inner ear move and vibrate
.
The result is a very quiet sound that our instrument can capture," said co-author Randall Blighe, Ph.
D.
, an associate professor in otolaryngology, head and neck surgery at the University of Washington School of Medicine who works at
Seattle Children's Hospital.
"This test is very sensitive, which means that if a patient has a hearing problem, they will be referred to a specialist for a more thorough evaluation
.
"

In the test, the doctor sends two different tones
to the ear at the same time.
Based on these tones, the hair cells in the ear vibrate and create a third tone, which is what
doctors listen to.

One reason this commercial device is expensive is that its speakers are designed to play two tones without interference
.
Researchers at the University of Washington have found that they can use affordable earbuds — each earbud plays one
of two tones.
These earbuds are connected to a microphone on a probe that can be placed in
the patient's ear.
The microphone records any sound coming from the ear and sends it to the smartphone for processing
.

"As you can imagine, these sounds coming out of the ears are so soft that sometimes it's hard to hear them in situations of environmental noise or the patient's head movement," said
lead author Justin Chan, a doctoral student at the University of Washington's Allen School.
"We designed algorithms on the phone that help us detect signals
in the presence of background noise.
These algorithms can run in real time on any smartphone and do not require the latest smartphone models
.
”

The researchers tested their device
at three hearing clinics in the Puget Sound area of Washington state.
In each test, they tested four different frequencies, which are typical for
this type of hearing screening.
Participants ranged
in age from a few weeks to 20 years old.

Now, the team is working with collaborators to use the tool as part of
the Newborn Hearing Screening Project in Kenya.
The researchers collaborated with a team from the Department of Global Health at the University of Washington, the University of Nairobi and the Kenyan Ministry of Health to create the Universal Hearing Screening for Newborns and Early Childhood in Kenya (TUNE) project
.

"Now, this is a prototype
we created.
The next challenge is to really scale up and then work with
local experts in each country who are most familiar with the specific challenges in each case.
"We have an opportunity to really make a difference in global health, particularly on newborn hearing
.
" I think it's
very reassuring to know that the research we're doing can help directly solve real problems.
”