by In an innovative approach to monitoring heart rate, Google and researchers from the University of Princeton and Rutgers University have proposed using ultrasound technology through the speaker drivers of active noise-canceling (ANC) headphones. The method, known as audioplethysmography (APG), involves sending low-intensity ultrasound signals through the ear canal and using feedback microphones to register the echo and detect minute changes caused by blood flow.
Traditionally, heart rate monitoring in wearables is conducted using light pulses to detect changes in blood volume. However, Google’s research suggests that ultrasound technology can be used to look for tiny deviations in the surface of the ear canal, offering a new way of monitoring heart rate.
The team discovered similarities between the waveforms produced by smartwatch sensors and the APG waveform after conducting mathematical analyses. The APG waveform provided a more detailed view of cardiac activities, including pronounced dicrotic notches that offer insights into the central artery system and blood pressure.
One of the advantages of using ultrasound signals is that they are inaudible to the wearer and are not affected by background music or poor earbud seals. However, initial tests revealed that body movement could have a negative impact on the accuracy of the readings. To overcome this, the researchers suggested employing multiple frequencies.
Field tests involving 153 participants demonstrated the high accuracy of the APG solution for heart rate detection and registering heart rate variability across various activity scenarios. The median error for heart rate detection was 3.21%, while the median error in inter-beat interval for heart rate variability was 2.70%.
The researchers believe that any true-wireless ANC headphones can be transformed into smart health monitors through a simple software update. While it may be tempting to speculate that this technology could be integrated into future Pixel Buds, regulatory approval will be required before implementation, indicating that it may take some time before consumers can experience the system in practice.
The research was presented at MobiCom 2023, and a detailed paper on the study is available through Google Research. This breakthrough in using ultrasound technology through ANC headphones has the potential to revolutionize heart rate monitoring and bring about advancements in wearable technology.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
