Method and device for detecting and locating a fault point of a housing

A device for detecting and locating a fault of a housing, comprising:

• at least two loudspeakers and at least two microphones for arrangement in an interior of the housing;
• and
• a signal generator connected to the loudspeakers and an evaluation circuit connected to the microphones;
• wherein the evaluation circuit is configured to:
• for each possible pairing of a loudspeaker and microphone:
• measure a reference frequency response of a sound transmission from the loudspeaker to the microphone of this pairing,
• for each pairing:
• measure a present frequency response of a sound transmission from the loudspeaker to the microphone of this pairing at a later point in time,
• for each pairing:
• determine a difference frequency response as a difference between the present frequency response of this pairing and the reference frequency response of this pairing,
• for at least one pairing:
• determine a detection measure of the difference frequency response of this pairing and, if this at least one detection measure satisfies a predetermined detection criterion:
• to detect a fault, and
• for each possible combination of two pairings:
• to calculate a correlation measure between the difference frequency responses of this combination, and then
• to determine the combination with the highest correlation measure and, if the same loudspeaker or the same microphone appears in the two pairings of this combination, then to localize the fault as being closer to this loudspeaker or microphone than to any other loudspeaker or microphone.