Light-based detection for acoustic applications
View Patent ↗A light-based skin contact detector is described, including a boot having an index of refraction less than or equal to another index of refraction associated with skin at a frequency of light, a light emitter and detector coupled to the boot and configured to measure an amount of light energy reflected by an interface of the boot, and a digital signal processor configured to detect a change in the amount of light energy reflected by the interface. Embodiments relate to methods for detecting skin contact by measuring an amount of energy reflected by an interface when a boot is not in contact with skin, measuring another amount of energy reflected by another interface when the boot is in contact with the skin, and detecting a change between the amount of energy and the another amount of energy using a digital signal processor.
1. A method, comprising:
measuring an amount of energy reflected by an interface using a light emitter and detector when a surface skin microphone (SSM) boot of a SSM is not in contact with skin, the SSM including a diaphragm coupled with a vibration transducer and the SSM boot;
measuring another amount of energy reflected by another interface using the light emitter and detector when the SSM boot is in contact with the skin; and
detecting skin contact by detecting a change between the amount of energy and the another amount of energy using a digital signal processor.
2. The method of claim 1 , wherein the amount of energy is greater than the another amount of energy.
3. The method of claim 1 , further comprising detecting speech after detecting the skin contact.
4. The method of claim 1 , wherein the energy comprises infrared light energy transmitted using infrared spectra.
5. The method of claim 1 , wherein an index of refraction of the SSM boot is less than and almost equal to another index of refraction of the skin.
6. The method of claim 1 , wherein the light emitter and detector comprises an infrared light-emitting diode pair.
7. The method of claim 1 , wherein the interface is between the SSM boot and air.
8. The method of claim 1 , wherein the another interface is between the SSM boot and the skin.
9. The method of claim 1 , wherein the SSM boot comprises a material having an index of refraction greater than or equal to another index of refraction of air.
10. The method of claim 1 , wherein the SSM boot comprises a material having an index of refraction greater than or equal to an air index of refraction and less than or equal to another index of refraction of the skin.
11. The method of claim 1 , wherein the detecting the change between the amount of energy and the another amount of energy is performed after a critical angle is increased.
12. The method of claim 1 , wherein the detecting the change between the amount of energy and the another amount of energy is performed after a critical angle is eliminated.
13. The method of claim 1 , wherein the light emitter and detector are coupled with a side of the SSM boot, and the SSM boot comprises a material that is optically transmissive to infrared light emitted by the light emitter and detector.
14. The method of claim 1 , wherein the vibration transducer includes a coupler having a contact device protruding from a side of the coupler.
15. The method of claim 1 , wherein the diaphragm is positioned between a contact device and an electret material, the electret material in contact with a backplate, the contact device protruding from a side of a coupler.
16. The method of claim 1 , wherein the vibration transducer includes a coupler having an acoustic impedance matched to an impedance of human skin.