Selectable sound frequency extractor for noisy environments - eliminates background noise using two microphones in tube into which tuning tube is screwed to select difference in microphone operation

摘要

The device extracts sound of a desired frequency from background noise and eliminates local parasitic noise. Two microphones of identical mechanical and electrical characteristics are contained in a tubular such that all sound or noise transmitted to, received or generated by the body is transmitted equally to both microphones. A coaxial member is viewed into the tubular body next to one microphone. The coaxial member serves as a tuning tube which affects the adjacent microphone to produce a difference between the operation of the microphones limited to the desired frequency or range. The tuning tube is typically quarter wavelength and can be screwed into or out of the body for adjustment.