A system for surveillance, comprising: an audio signal analyser, wherein the audio signal analyser is configured to receive two or more audio microphone signals, wherein the audio signal analyser is configured to determine a first pattern matching result by determining whether the two or more audio microphone signals comprise at least one audio pattern of one or more predefined audio patterns; an air pressure signal analyser, wherein the air pressure signal analyser is configured to receive an air pressure change signal indicating an air pressure change, or is configured to receive an air pressure signal indicating a current air pressure; wherein the air pressure signal analyser is configured to determine a second pattern matching result by determining whether the air pressure signal or the air pressure change signal comprises at least one pressure sensor pattern of one or more predefined pressure sensor patterns; wherein the audio signal analyser is configured to determine the first pattern matching result by determining whether each one of the two or more audio microphone signals comprises said at least one audio pattern of one or more predefined audio patterns; wherein an evaluator is configured to indicate that a predefined event occurred, if the first pattern matching result indicates that said at least one of the one or more predefined audio patterns is found in each of the two or more audio microphone signals, and if the second pattern matching result indicates that said at least one of the one or more predefined pressure sensor patterns is found in the air pressure signal or in the air pressure change signal. an audio signal analyser, wherein the audio signal analyser is configured to receive two or more audio microphone signals, wherein the audio signal analyser is configured to determine a first pattern matching result by determining whether the two or more audio microphone signals comprise at least one audio pattern of one or more predefined audio patterns; an air pressure signal analyser, wherein the air pressure signal analyser is configured to receive an air pressure change signal indicating an air pressure change, or is configured to receive an air pressure signal indicating a current air pressure; wherein the air pressure signal analyser is configured to determine a second pattern matching result by determining whether the air pressure signal or the air pressure change signal comprises at least one pressure sensor pattern of one or more predefined pressure sensor patterns; wherein the audio signal analyser is configured to determine the first pattern matching result by determining whether each one of the two or more audio microphone signals comprises said at least one audio pattern of one or more predefined audio patterns; wherein an evaluator is configured to indicate that a predefined event occurred, if the first pattern matching result indicates that said at least one of the one or more predefined audio patterns is found in each of the two or more audio microphone signals, and if the second pattern matching result indicates that said at least one of the one or more predefined pressure sensor patterns is found in the air pressure signal or in the air pressure change signal.