| Abstract: | A method for detecting a change in an environment is disclosed. The method includes forming a test acoustic signal based on time-reversal of a baseline acoustic signal after the baseline acoustic signal has traversed the environment while the environment is in a baseline condition. The method also includes detecting the test acoustic signal after the test acoustic signal has traversed the environment while the environment is in an unknown condition. The method includes determining whether there has been a change in the environment by comparing the baseline acoustic signal with the detected test acoustic signal after the test acoustic signal has traversed the environment while the environment is in the unknown condition. |