Abstract: In some embodiments, an apparatus and a system, as well as a method and article, may operate to substantially simultaneously measure acoustic radiation from a source in a geological formation, at each of at least two sensors in an array, over a selected time period to provide acoustic pressure measurements. Further activity may comprise locating the source at a location in the geological formation with respect to the sensors by determining acoustic intensity associated with the source, based on the acoustic pressure measurements, independent of medium sound velocity in one or more media disposed between the sensors and the source. Additional apparatus, systems, and methods are disclosed.