Abstract: A method and apparatus for remote optical detection of a gas present in an observed volume using a thermal imager or camera including one or more sensitive elements which are sensitive to radiant fluxes in a determined band of wavelengths, two filters interposable on the optical axis of the camera, the filters having similar transmission bands, one of which includes an absorption line characteristic of the looked-for gas, while the other of which is complementary to said absorption line, and signal processing means for taking the difference between the radiated fluxes received from two points at different temperatures in the volume as observed first through one of the filters and then through the other filter, for taking the ratio of said differences, and for deducing therefrom whether the gas is present in the observed volume.

Abstract: A single-channel nerve stimulating device for auditory prosthesis for improving the conversational capacity of a profoundly deaf person is described. The single-channel device of simple construction provides detailed information to the patient's nervous system. The device comprises a microphone designed to pick up a sound signal and electronic processor which converts the sound signal into an electrical signal.