Abstract: A distributed acoustic sensor utilizing a Fizeau type fiber optic transducer and a distributed acoustic collector to gather and return acoustic disturbances from remote areas in buried, underground, or underwater installations. A light beam from a laser or LED source is transmitted over a fiber to a remote transducer which is coupled to a distributed acoustic collector. The collector may be an extended pipe or tube system filled with an acoustic conducting medium such as air or an appropriate liquid which communicates with the sensing diaphragm in the transducer. An interference beam whose characteristics are a function of the diaphragm motion is created in the transducer and transmitted back over the common single fiber toward the source. An in-line optical coupler/splitter diverts a portion of the returning modulated beam to a photodetector which outputs a proportional electrical signal to an electronic circuit for amplification and analysis.