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The Reasons We Choose to Put PPG Technology in the Ear



Health Trend: Monitor Your Health Anytime and Anywhere


In this fast-paced world, people are putting more and more emphasis on convenience and efficiency, from things as minor as ordering food, to things as major as managing their health. Thanks to the rapid technological advancement in healthcare, it has been easier for individuals to monitor and track their health. This has given rise to wearable technology, and smartwatches have been at the forefront of this revolution, yet it is crucial to recognize that “hearable” is a rising technology that deserves equal attention.


“Hearable”, to put it simply, is a type of wearable technology that is specifically designed for audio-related functions incorporated with health monitoring capabilities. Our company specializes in developing hearables with our in-ear PPG (photoplethysmography) sensors, which can detect bio-signals and measure vital signs, including but not limited to heart rate, core body temperature, respiratory rate, blood oxygen saturation (SpO2), and heart rate variability (HRV).



Why Hearables but Not Smartwatches?


In fact, a lot of wearables utilize PPG technology to collect health data, including smartwatches and hearables, due to its non-invasive and user-friendly nature. If you have worn a smartwatch before, you may notice some green lights emitting from the back of the watch, and that is actually how PPG works. 


PPG device contains a light source and a photodetector, the former emits light onto a tissue and the latter measures the reflected light. The light reflection helps evaluate changes in blood circulation volume. This kind of data always provides valuable information related to the cardiovascular system, common examples are pulse rate and SpO2.


However, we choose to place PPG technology in the ear because we believe it can generate more accurate data. Particularly, our company employs medical infrared light for the in-ear PPG technology because it has high accuracy in cold weather and dark skin when compared to the green light used in most smartwatches. Below is to show more reasons why we put the PPG technology in the ear instead of the wrist.


  • Stronger Signal

Ears have larger blood vessels and jugular veins, which means a richer blood supply. This increased blood flow and density of blood vessels contribute to stronger PPG signals. Besides, the higher proximity to the carotid artery allows more direct detection of arterial pulsations, which is also a factor of stronger PPG signals. Furthermore, the ear contains thinner and more translucent tissues compared to other body parts. This enables better light penetration and reflection, again resulting in stronger PPG signals.


  • Cleaner Signal 

In-ear PPG technology can detect cleaner signals because there are less muscles in the ear, therefore less external interference and less motion artifacts that can affect signal quality.


  • More Stable Point of Signal Reference

The wearing position of earbuds is more consistent while smartwatches can be worn tight or loose, high or low. The more consistent the wearing position, the higher the accuracy of the bio-signal detection.


  • Alternative to Smartwatch

Apart from the scientific reasons above, the reality is that there is a group of people out there who are not a fan of smartwatches. Reasons can vary from finding them bulky, uncomfortable to wear to not aesthetically appealing. Hearables come in handy especially in exercise scenarios since it is common to see people listening to music with earphones during exercise. In that case, health monitoring is merely an add-on feature with no burden added to them. Plus, earphones are more comfortable to wear when there is sweat.



The emergence of hearables has made earbuds more than just a device to listen to music; but also a means to measure vital signs, which offers a whole new level of functionality and convenience. Our company in the future hopes to adopt our hearables in more healthcare scenarios to cater different healthcare needs, and to shape the future of health with Hera Leto.


Editor: Michelle Au


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