Abstract: The present disclosure is directed at methods, apparatuses, and techniques for detecting an acoustic event along a channel. Different wavelengths of an optical signal are multiplexed along a fiber optic strand extending along the channel. The strand has groups of transducers located along its length, and all of the transducers in any one of the groups reflect a tuned wavelength when not under strain. The wavelength that the transducers reflect changes in response to strain. Optical signal processing equipment receives reflected optical signals from the groups of transducers, and determines, for each of the groups of transducers, differences between wavelengths of the optical signals reflected by the transducers of that group and the tuned wavelength for that group. The differences correspond to the loudness of the event measured by that group of transducers, which can then be graphically represented to a person for analysis.