Shulou(Shulou.com)11/24 Report--

CTOnews.com, October 29 (Xinhua) currently, heart rate monitoring techniques in wearable devices such as smartwatches or wireless headphones rely on photoelectric plethysmography (PPG), which uses light pulses to measure blood activity. This method works well, but it also has its limitations. Google scientists wrote in a new research blog yesterday that they have tried a different method called acoustoelectric plethysmography (APG), which uses ultrasound to measure heart rate, and they only use active noise reduction (ANC) headphones and a software update on the market.

The principle of this technique is to emit a low-intensity ultrasonic signal into the ear canal and then use a miniature microphone to help achieve active noise reduction to detect skin surface perturbations caused by blood flow. According to the blog, the technique is "stable" even in cases of poor earseal, different sizes of the ear canal or darker skin. The last point is worth noting because the accuracy of heart rate detection in smartwatches and other wearable devices has always been a problem for people with darker skin or tattoos.

Google researchers also found that ultrasound methods also work when playing music, but they say there are problems in noisy environments. "APG signals can sometimes be very noisy and can be seriously disturbed by body movement." However, they found that motion problems could be overcome by using multiple frequencies and filtering out the most accurate signals.

In addition to the commercially available headphones, the researchers also used specially made prototype headphones to test the impact of microphone position. With 153 participants in the field study, the researchers said the median error rates for heart rate and heart rate variability were 3.21% and 2.70%, respectively.

Headphones with heart rate monitoring are already on the market, but they use the PPG method and are sensitive to strenuous exercise or inappropriate wearing.

What CTOnews.com needs to point out is that this is just a study, and it doesn't mean Google is about to launch headphones with this feature.

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