Google Researchers Develop Software Update to Transform TWS ANC Headphones into Heart Rate Monitors
Google researchers have made a groundbreaking discovery that could revolutionize the way heart rate monitors are built. Through a software update, Google has developed a system that can transform true wireless stereo (TWS) active noise canceling (ANC) headphones into heart rate monitors. This new method, called Audioplethysmography (APG), utilizes ultrasound emitted by the earphone’s speaker driver to detect minuscule alterations in the ear canal’s surface.
The researchers presented their findings in a paper titled “APG: Audioplethysmography for Cardiac Monitoring in Hearables” at MobiCom 2023. According to the paper, APG allows ANC hearables to track physiological signals like heart rate and heart rate variability without the need for additional sensors or compromising battery life.
Traditional smartwatches use light pulses to monitor heart rate, but Google’s research suggests that the ear canal’s unique physiological response makes it an ideal location for health sensing. The deep ear artery, responsible for supplying blood to the auditory canal, has intricate connections with smaller vessels that permeate the canal. Even the subtle variations in the shape of these blood vessels caused by the heartbeat and blood pressure can lead to minute alterations in the volume and pressure of the ear canals.
Previous research has focused on integrating multiple sensors into hearables for health monitoring, but this approach presents challenges such as additional costs, weight, power consumption, and complexity in acoustic design. Google’s APG method overcomes these hurdles by emitting a low-intensity ultrasound probing signal through an ANC headphone’s speakers. This signal triggers echoes, which are received via on-board feedback microphones. The echoes are modulated by subtle displacements of the ear canal skin and heartbeat vibrations.
APG offers a unique advantage by transmitting multiple frequencies simultaneously, allowing for a higher-quality signal and greater resilience to motion. Extensive user experience studies conducted by Google with 153 participants showed that APG consistently delivers accurate heart rate and heart rate variability measurements. Furthermore, APG proves to be resilient to variations in skin tone, sub-optimal seal conditions, and ear canal size, unlike traditional photoplethysmogram (PPG) monitoring.
“APG transforms any TWS ANC headphones into smart sensing headphones with a simple software upgrade, and works robustly across various user activities,” said Google in a blog post. This discovery represents a significant advancement in biomedical and mobile research, unlocking new possibilities for low-cost health sensing.
It is worth noting that this research is proprietary to Google and should not be reproduced without permission.
Furthermore, Google has recently announced other innovative projects, such as AR Beauty Ads, which aim to transform the shopping experience, and AI-powered search advertising potential. These advancements demonstrate Google’s commitment to pushing the boundaries of technology and enhancing user experiences.
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