White noise listening device for monitoring infant breathing

By Dr. Ananya Mandal, MDOct 15 2019

Researchers at the University of Washington have come up with a device which acts as a monitor for infant breathing patterns while playing white noise to soothe them to sleep. The results of their study with the new device would be presented in an article titled, “Contactless Infant Monitoring using White Noise,” at the MobiCom 2019 conference in Los Cabos, Mexico on the 22nd of this month.

UW researchers have developed a new smart speaker skill that lets a device use white noise to both soothe sleeping babies and monitor their breathing and movement.Dennis Wise/University of Washington

The new device called BreathJunior is essentially a smart speaker device that plays white soothing noise and in turn also records the noise that is reflected back to it after getting deflected back from the sleeping babies’ small chests. They tested their device and its success on five babies at a local hospital’s NICU (neonatal intensive care unit) found that the device gave out reports that closely matched other monitors that were attached to the babies’ chests.

According to the researchers, the uniqueness of the device was their contactless nature. Most other monitors require to be hooked up to the babies’ bodies in order to provide recordings. Co-author Dr. Jacob Sunshine, an assistant professor of anesthesiology and pain medicine at the UW School of Medicine, in a statement said, “One of the biggest challenges new parents face is making sure their babies get enough sleep. They also want to monitor their children while they're sleeping. With this in mind, we sought to develop a system that combines soothing white noise with the ability to unobtrusively measure an infant's motion and breathing.”

Co-author Shyam Gollakota, an associate professor in the UW's Paul G. Allen School of Computer Science & Engineering and the director of the UW computing for health group, added that they made the system easy to use and run on a smart speaker such as Amazon Echo. He said, “Smart speakers are becoming more and more prevalent, and these devices already have the ability to play white noise. If we could use this white noise feature as a contactless way to monitor infants' hand and leg movements, breathing and crying, then the smart speaker becomes a device that can do it all, which is really exciting.”

Speaking on white noise, first author Anran Wang, a doctoral student in the Allen School explained that there are several frequencies of sounds that are used to produce an overall soothing sound. This can cover sudden sounds that could wake the baby up. The white noise contains different sound frequencies. They needed to find out the difference between the white noise that was sent out and the noise that was deflected back to the speaker/recorder from the babies’ bodies. This could be possible via the microphones attached within the speaker said Wang. Wan added in a statement, “We start out by transmitting a random white noise signal. But we are generating this random signal, so we know exactly what the randomness is. That signal goes out and reflects off the baby. Then the smart speaker's microphones get a random signal back. Because we know the original signal, we can cancel out any randomness from that and then we're left with only information about the motion from the baby.”

One of the greatest problems in infant breathing monitoring said Wang was the small movements of the infant chest compared to the perceptibly larger movements of adult chests. Further the speaker would also have to differentiate between larger movements of the baby moving around the crib and the smaller movements of their breathing chests. The speakers would also pick up the crying noises of the babies.

The speakers thus had to positioned carefully so that even the smallest sound waves could be deflected back to the microphones Wang explained. He added, “The breathing signal is so weak that we can't just look for a change in the overall signal we get back. We needed a way to scan the room and pinpoint where the baby is to maximize changes in the white noise signal.

Our algorithm takes advantage of the fact that smart speakers have an array of microphones that can be used to focus in the direction of the infant's chest. It starts listening for changes in a bunch of potential directions, and then continues the search toward the direction that gives the clearest signal.”

The team wrote, “The key enabler underlying our system is a set of novel algorithms that can extract the minute infant breathing motion as well as position information from white noise which is random in both the time and frequency domain.”

As their first step they created a prototype smart speaker to test BreathJunior on an infant simulator. The simulator was set to breathe at different rates. Each of these various rates ranging from slow 20 breaths per minute to 60 breaths per minute, were picked up by the BreathJunior. Abnormal breathing patterns could also be detected using the BreathJunior. This would be helpful for babies born prematurely said the experts. In both scenarios BreathJunior performed successfully, the team wrote. Next they tried their device on real babies in the NICU. The accuracy of the device was seen up to 65 breaths per minute. The authors of the study wrote, “Our study demonstrates that the respiratory rate computed by our system is highly correlated with the ground truth with a correlation coefficient of 0.938.”

Co-author Sunshine explained, “Infants in the NICU are more likely to have either quite high or very slow breathing rates, which is why the NICU monitors their breathing so closely. BreathJunior holds potential for parents who want to use white noise to help their child sleep and who also want a way to monitor their child's breathing and motion. It also has appeal as a tool for monitoring breathing in the subset of infants in whom home respiratory monitoring is clinically indicated, as well as in hospital environments where doctors want to use unwired respiratory monitoring.” He added as a disclaimer, “However, it is very important to note that the American Academy of Pediatrics recommends not using a monitor that markets itself as reducing the risk of sudden infant death syndrome, and this research and the team makes no such claim.”

Gollakota said, “In just a few years, we have come a long way from monitoring large motions in adults to extracting the tiny motion of a newborn infant's breathing. This has been possible because of algorithmic innovations as well as advances in smart speaker hardware. Looking ahead, one can envision transforming a smart speaker into a 'medical tricorder' that can contactlessly monitor a variety of vital signs beyond just breathing.”

The technology could soon be commercialized by Sound Life Sciences, Inc. – a start up from UW. The study was funded by the National Science Foundation.