Google Measures Heart Rate with Noise-Canceling Headphones: Scientists at Google have successfully used audioplethysmography (APG), a method that uses ultrasound to measure heart rate, to track heart health with wearable tech that doesn’t require extra sensors or shorten battery life.
The group did two runs of user experience studies with 153 people.
The data show that APG consistently measures heart rate accurately (3.21 percent of the time, across all activity scenarios) and heart rate variability accurately (2.70 percent of the time, between beats).
Google Measures Heart Rate with Noise-Canceling Headphones!
People often wear headphones and earbuds not only to listen to music, but also to work out, concentrate, or just change their mood.
“We have introduced a novel active in-ear health sensing modality. APG enables ANC hearables to monitor a user’s physiological signals, such as heart rate and heart rate variability, without adding extra sensors or compromising battery life,” Google researchers said in a blog post.
As long as APG stays 80 decibels below the limit set by safety rules, doesn’t change based on seal conditions, and works for all skin tones.
When passively listening in the ear canal, the quality of the sound depends a lot on how well the earbuds seal.
It is hard to add health functions to commercial ANC headphones that depend on passively listening to low frequency signals.
“APG bypasses the aforementioned ANC headphone hardware constraints by sending a low intensity ultrasound probing signal through an ANC headphone’s speakers,” said Xiaoran “Van” Fan, Experimental Scientist and Trausti Thormundsson, Director, Google.
This signal causes echoes, which are picked up by feedback mics built into the board. We see that the heartbeat and the tiny skin movements in the ear canal change these ultrasound sounds.
“The final APG waveform looks strikingly similar to a photoplethysmograms (PPG) waveform, but provides an improved view of cardiac activities with more pronounced dicrotic notches (pressure waveforms that provide rich insights about the central artery system, such as blood pressure),” they explained.
In their first tests, they saw that APG works well even when the earbuds don’t lock properly and music is playing.
“However, we noticed the APG signal can sometimes be very noisy and could be heavily disturbed by body motion. At that point, we determined that in order to make APG useful, we had to make it more robust to compete with more than 80 years of PPG development,” said the team.
APG transforms any TWS ANC headphones into smart sensing headphones with a simple software upgrade, and works robustly across various user activities, the researchers added.