Dual-ear heart rate detection system using asymmetry
Methods and apparatuses for heart rate detection are described. In one example, a headphones apparatus and method includes emitting a first light in a first light direction directed at a left ear location from a left ear light emitter, and detecting a detected first light at a left ear light detector following interaction of the first light with a left ear tissue. The method includes emitting a second light in a second light direction directed at a right ear location from a right ear light emitter, the right ear location different from the left ear location. The method further includes detecting a detected second light at a right ear light detector following interaction of the second light with a right ear tissue, and estimating a heart rate from the detected first light and the detected second light.
1. A method comprising:
emitting a first light in a first light direction directed at a left ear location from a left ear light emitter;
detecting a detected first light at a left ear light detector following interaction of the first light with a left ear tissue;
determining a first wearer heart rate utilizing the detected first light;
receiving a left accelerometer sensor output indicating a left ear direction of motion;
emitting a second light in a second light direction directed at a right ear location from a right ear light emitter, wherein the right ear location is different from the left ear location or the second light direction is different from the first light direction;
detecting a detected second light at a right ear light detector following interaction of the second light with a right ear tissue;
determining a second wearer heart rate utilizing the detected second light;
receiving a right accelerometer sensor output indicating a right ear direction of motion;
applying a left weight factor to the first wearer heart rate comprising utilizing the left accelerometer sensor output to generate a weighted first heart rate;
applying a right weight factor to the second wearer heart rate comprising utilizing the right accelerometer sensor output to generate a weighted second heart rate; and
determining a composite wearer heart rate utilizing the weighted first heart rate and the weighted second heart rate.
2. The method of claim 1 ,
applying the left weight factor to the first wearer heart rate comprises identifying a first quality of the detected first light from the left ear direction of motion and the first light direction; and
applying the right weight factor to the second wearer heart rate comprises identifying a second quality of the detected second light from the right ear direction of motion and the second light direction.
3. The method of claim 1 , further comprising:
determining a left ear ambient light level proximate or at the left ear light detector; and
determining a right ear ambient light level proximate or at the right ear light detector, wherein:
applying the left weight factor to the first wearer heart rate further comprises identifying a first quality of the detected first light from the left ear ambient light level; and
applying the right weight factor to the second wearer heart rate further comprises identifying a second quality of the detected second light from the right ear ambient light level.
4. The method of claim 1 , wherein the left ear location comprises a tragus area or an anti-tragus area and the right ear location comprises a concha area.
5. The method of claim 1 , wherein the left ear location comprises a concha area and the right ear location comprises a tragus area or an anti-tragus area.
6. The method of claim 1 , wherein the left ear light emitter and the left ear light detector are components of a left photoplethysmographic sensor and the right ear light emitter and the right ear light detector are components of a right photoplethysmographic sensor.
7. The method of claim 1 , wherein the first light direction is substantially perpendicular to the second light direction.
8. The method of claim 1 , wherein the first light direction is along an x-axis and the second light direction is along a y-axis or a z-axis with respect to a wearer head.
9. The method of claim 1 , wherein the first light direction is along a y-axis and the second light direction is along an x-axis or a z-axis with respect to a wearer head.
10. The method of claim 1 , wherein the first light direction is along a z-axis and the second light direction is along an x-axis or a y-axis with respect to a wearer head.
11. One or more non-transitory computer-readable storage media having computer-executable instructions stored thereon which, when executed by one or more processors, cause the one more processors to perform operations comprising:
emitting a first light in a first light direction directed at a left ear location from a left ear light emitter;
detecting a detected first light at a left ear light detector following interaction of the first light with a left ear tissue;
determining a first wearer heart rate utilizing the detected first light;
receiving a left accelerometer sensor output indicating a left ear direction of motion;
emitting a second light in a second light direction directed at a right ear location from a right ear light emitter, wherein the right ear location is different from the left ear location or the second light direction is different from the first light direction;
detecting a detected second light at a right ear light detector following interaction of the second light with a right ear tissue;
determining a second wearer heart rate utilizing the detected second light;
receiving a right accelerometer sensor output indicating a right ear direction of motion;
applying a left weight factor to the first wearer heart rate comprising utilizing the left accelerometer sensor output to generate a weighted first heart rate;
applying a right weight factor to the second wearer heart rate comprising utilizing the right accelerometer sensor output to generate a weighted second heart rate; and
determining a composite wearer heart rate utilizing the weighted first heart rate and the weighted second heart rate.
12. The one or more non-transitory computer-readable storage media of claim 11 , wherein:
applying the left weight factor to the first wearer heart rate comprises identifying a first quality of the detected first light from the left ear direction of motion and the first light direction; and
applying the right weight factor to the second wearer heart rate comprises identifying a second quality of the detected second light from the right ear direction of motion and the second light direction.
13. The one or more non-transitory computer-readable storage media of claim 11 , the operations further comprising:
determining a left ear ambient light level proximate or at the left ear light detector; and
determining a right ear ambient light level proximate or at the right ear light detector, wherein:
applying the left weight factor to the first wearer heart rate further comprises identifying a quality of the detected first light from the left ear ambient light level; and
applying the right weight factor to the second wearer heart rate further comprises identifying a quality of the detected second light from the right ear ambient light level.
14. The one or more non-transitory computer-readable storage media of claim 11 , wherein the left ear location comprises a tragus area or an anti-tragus area and the right ear location comprises a concha area.
15. The one or more non-transitory computer-readable storage media of claim 11 , wherein the left ear location comprises a concha area and the right ear location comprises a tragus area or an anti-tragus area.
16. The one or more non-transitory computer-readable storage media of claim 11 , wherein the left ear light emitter and the left ear light detector are components of a left photoplethysmographic sensor and the right ear light emitter and the right ear light detector are components of a right photoplethysmographic sensor.
17. The one or more non-transitory computer-readable storage media of claim 11 , wherein the first light direction is substantially perpendicular to the second light direction.
18. The one or more non-transitory computer-readable storage media of claim 11 , wherein the first light direction is along an x-axis and the second light direction is along a y-axis or a z-axis with respect to a wearer head.
19. The one or more non-transitory computer-readable storage media of claim 11 , wherein the first light direction is along a y-axis and the second light direction is along an x-axis or a z-axis with respect to a wearer head.