Cardiac arrhythmia and other conditions affecting the heart are best discovered early to avoid complications and serious ailments. Some ofour favorite fitness trackersalready incorporate heart rate detection hardware and blood oxygen trackers, while the industry is nowaiming for blood pressure monitoringas well. Google researchers have the data to suggest that another wearable — earbuds with Active Noise Cancelation (ANC) — are also just a few software updates away from detecting heart rate accurately.
Wrist-worn wearables from almost every major manufacturer usually deliver reliable heart rate data. A companion app like Google Fit then crunches data over time to show you patterns and irregularities which could be a cause for concern. Although the system works well,Google researchersrecentlypublished technical papersdetailing a method of cardiac monitoring called Audioplethysmography (APG) (via9to5Google). As the name suggests, this method uses audio equipment like earbuds, simply because market trends reveal audio gear sells a lot more than wrist-worn wearables like fitness trackers and smartwatches.
Google notes that the volume of your ear canal changes slightly with every heartbeat, thanks to the deformation of blood vessels. So, the speaker driver of an earbud can pump some ultrasonic sound waves of multiple special frequencies and pick up the reverberation using feedback microphones, also housed in the earbuds. Just like how sonar works in a submarine, a mathematical model is then used to calculate the time and variation between the received echoes, thereby calculating the ear canal’s variations in volume. These variations are directly related to your cardiac rhythm.
The earbud wearer should not realize heart rate detection is underway because ultrasound waves are outside the audible frequency range an eardrum can pick up. Moreover, ultrasound isn’t an alien concept — it is widely used for imaging fetuses in the womb. Google is merely using the same concept, with APG sound waves tuned to detect your heart rate accurately. Google evaluated its APG model with 153 participants over an eight-month period, and APG was consistently accurate in measuring the wearer’s heart rate and its variations likedicrotic notches.
Interestingly, there are two major advantages of this method has over existing technologies. First, it doesn’t need additional hardware, and the ANC earbuds sitting in your pocket right now could pick up your heart data with just a simple software update. Secondly, Google’s measurement technique is immune variations in ear canal size, and the quality of the seal your earbuds achieve. APG also trumps photoplethysmogram (PPG) sensors in wrist-worn wearables, which areaffected by the wearer’s skin tone.
We hope to see this tech in the next generation ofGoogle’s Pixel Buds, although it’s safe to assume the feature will be limited to the Pro models which boast of ANC. Google also has the option of making this technology available to other audio gear brands through licensing or open-source documentation.
