US Patent 11278215 Rhinometric sensing and gas detection

An acoustic system can track gas emissions by exploiting the nostril-accessible nasal pathways of an animal. Actuators and microphones used in the apparatus can be similar to those currently found in cell phones, which in turn make the acoustic apparatus small and rugged. The nostril geometry can be mapped using sound waves, similar to the mapping done by an acoustic rhinometer. Where acoustic rhinometers assume a constant speed of sound to measure changes in geometry, acoustic approaches as disclosed herein can assume constant geometry to measure changes in the speed of sound. Approaches disclosed here are particularly useful with any gas, such as (for example) methane, hydrogen, helium, etc. that has a speed of sound higher than other typical gaseous components of exhaled air, such as nitrogen, carbon-dioxide, oxygen, etc.