Checking the hearing of newborns can be challenging, in that the infants can't tell you which sounds they do or don't hear. A new system offers an inexpensive solution to that problem, by utilizing a smartphone, earbuds and a simple microphone.
In most First World nations, newborn babies are routinely screened for hearing loss using a machine that simultaneously plays two tones into each ear via a single speaker. If the ear has normal hearing, the hair cells in it will vibrate in response to those combined tones, creating a third tone. The machine detects that third tone, letting clinicians know that everything's OK in that ear.
Unfortunately, though, such machines are too costly to be widely used in developing nations. As a result, if an infant is deaf, their parents may not know until they've spent quite some time unsuccessfully trying to develop the child's language skills. That's where the new system comes in.
Developed by scientists at the University of Washington, it utilizes two off-the-shelf earbuds that separately play back the initial two tones. The two earbuds are connected via acoustic hosing to a single probe, which also contains a small commercially available microphone.
The probe is placed in each ear (one after the other) like a single earbud, where it simultaneously plays back the first two tones and listens for the third. It's connected via a single plug to a smartphone, which is running a custom app.
"As you can imagine, these sounds that are coming out from the ear are very soft, and sometimes it’s hard to hear them over noise in the environment or if the patient is moving their head," said doctoral student Justin Chan, lead author of the study. "We designed algorithms on the phone that help us detect the signal even with all that background noise. These algorithms can run in real time on any smartphone and do not require the latest smartphone models."
The technology was used to test the hearing of 114 patients – 52 of whom were babies up to six months old – at three hearing clinics in Washington state. It was found to be just as accurate as the traditional machine, identifying all of the patients who had hearing loss. Plans now call for the setup to be put to use within a newborn hearing screening project in Kenya.
"We have an opportunity to really have an impact on global health, especially for newborn hearing," said Chan. "I think it’s pretty gratifying to know that the research we do can help to directly solve real problems."
A paper on the research was recently published in the journal Nature Biomedical Engineering.
Source: University of Washington
