In a distance measuring system, electronic means and electroacoustic hardware means, said electroacoustic hardware means capable of operating in high-pressure and/or high temperature, said electroacoustics hardware containing transmit transducer means, mounted in a known location, for radiating an acoustical signal into a gaseous environment after receiving a transmit excitation signal from said electronics means, receiving transducer means, which could be the same instrument as the transmit transducer, also mounted in a known location, for receiving an echo from said acoustic signal after it reflects from the surface of an object or substance in the gaseous medium, and turning said acoustic signal into an electronic signal, said electronic hardware having means capable of detecting said received echo electronic signal and means to measure the time from when said transmit excitation signal was sent until when said echo signal was received, and means for calculating the location of the reflecting object or substance using the known location of the transmitting and receiving transducer and the speed of sound.