An acoustic sensor for sensing environmental attributes within an enclosure is disclosed. The acoustic sensor may include a bulk acoustic wave (BAW) transducer configured to be installed outside the enclosure. The BAW transducer may generate an acoustic wave pulse and receive a reflected acoustic wave pulse. The acoustic sensor may further a waveguide assembly configured to be installed inside the enclosure. The waveguide assembly configured to receive the acoustic wave pulse from the BAW transducer. The acoustic sensor may further include a sensing device, wherein the sensing device may determine a change in one or more acoustic wave propagation parameters, based on the generated acoustic wave pulse and the reflected acoustic wave pulse. The sensing device may further determine one or more environmental attributes within the enclosure, based on the change in the one or more acoustic wave propagation parameters.