Acoustic signal response in solid structures measured by distributed acoustic sensing

This paper investigates the propagation of acoustic waves in solid media using a distributed acoustic sensing (DAS) system. An optical fiber is embedded in a plastic cable raceway, which is subjected to sound stimuli generated by a loudspeaker and mechanical impulses. The DAS system is configured to sample the backscattered signal with a spatial resolution of 1 meter along the fiber. By triggering the acoustic excitation at various positions relative to the fiber, the resulting DAS traces are analyzed to evaluate the temporal and spatial response of the system. The measurements reveal that the DAS response is close to being uniform along the sensing fiber. While local effects cannot be excluded, the results suggest that sound propagation through the solid structure does not introduce a dominant distortion or delay of the signal in the investigated configuration. Consequently, for the purposes of localization and event detection in such setups, the influence of acoustic wave propagation within the supporting medium appears to be limited.