Detection and classification of abnormal sounds

1. A system comprising:

a primary audio surveillance node including a control unit, the control unit configured to:

receive a sound input based on a sound emitted by a source and detected by a microphone configured to detect sound and acoustic pulses;

receive an acoustic pulse input based on an acoustic pulse provided by a secondary audio surveillance node and detected by the microphone;

determine a relative location of the primary audio surveillance node with respect to the secondary audio surveillance node based on the acoustic pulse;

determine a location of the source of the detected sound based on the sound input and the determined relative location; and

classify the detected sound based on a characteristic of the detected sound and the determined location of the source.

2. The system of claim 1 , wherein the primary audio surveillance node further comprises a speaker configured to emit acoustic pulses, and a wireless transceiver configured to transmit time-of-emission data for each acoustic pulse emitted by the speaker and receive time-of-emission data for each acoustic pulse provided by the secondary audio surveillance node.

3. The system of claim 1 , wherein the control unit is further configured to determine a time-of-flight for each detected acoustic pulse.

4. The system of claim 1 , wherein the primary audio surveillance node further comprises a wireless transceiver configured to transmit time-of-flight data for each detected acoustic pulse and receive time-of-emission data for an acoustic pulse detected by another audio surveillance node.

5. The system of claim 1 , wherein the determination of the relative location of the primary audio surveillance node is based on a plurality of time-of-flight data.

6. The system of claim 1 , wherein the primary audio surveillance node further comprises a wireless transceiver configured to transmit a signal based on the detected sound and receive a signal from a monitoring device regarding an audio response, wherein the control unit is configured to provide the audio response using a speaker of the primary audio surveillance node.

7. The system of claim 1 , wherein the control unit is configured to provide an alert, the alert including audio received from a monitoring device.

8. The system of claim 1 , wherein the control unit is configured to provide an alert, the alert including at least one of an image and a video.

9. The system of claim 1 , wherein the control unit is configured to determine the location of the source based on a characteristic of the detected sound, the sound characteristic at least one of a time of arrival, a relative intensity, a relative spectral content, and a triangulation.

10. The system of claim 1 , wherein the control unit is configured to automatically direct the microphone toward the determined location of the source.

11. The system of claim 1 , wherein the primary audio surveillance node further comprises a camera, and wherein the camera is at least one of a video camera, a still camera, or a spectral camera.

12. The system of claim 11 , wherein the control unit is configured to automatically direct the camera toward the determined location of the source.

13. A method comprising:

receiving, by a control unit, a plurality of inputs from a plurality of nodes, wherein the plurality of inputs are based on a sound detected by a microphone;

determining, by the control unit, a location of a source of the detected sound based on the plurality of inputs;

classifying, by the control unit, the detected sound based on a characteristic of the detected sound and the location of the source; and

providing, by the control unit, an alert to a monitoring device regarding the detected sound based on the classification.

14. The method of claim 13 , further comprising transmitting a signal based on the detected sound and receiving a signal from the monitoring device regarding an audio response.

15. The method of claim 13 , wherein the microphone is a directional microphone.

16. The method of claim 13 , further comprising providing an audio response using a speaker of a node of the plurality of nodes, wherein the speaker includes one of a wide angle speaker, a directional speaker, or a directional speaker using nonlinearly downconverted ultrasound.

17. The method of claim 13 , further comprising receiving, by the control unit, an image captured by a camera, wherein the camera is at least one of a video camera, a still camera, or a spectral camera.

18. The method of claim 17 , further comprising automatically directing the microphone based on the image.

19. The method of claim 13 , wherein the classification is based on a predefined alert condition.

20. The method of claim 19 , further comprising altering the predefined alert condition based on a time of day.

21. The method of claim 19 , wherein the predefined alert condition comprises a first alert condition and a second alert condition, and wherein the first alert condition is applied to a first node and a second alert condition is applied to a second node.

22. The method of claim 21 , wherein the applied alert condition is based on the location of the node.

23. The method of claim 13 , further comprising determining the location of at least a first node of the plurality of nodes based on an acoustic pulse transmitted by a speaker of a second node and received by a microphone of at least one of the first node and a third node.

24. The method of claim 13 , further comprising detecting, by the control unit, a moving audio shadow caused by a portion of the source being blocked.

25. A method for detecting and classifying sounds, comprising:

receiving, by a control unit, sound data from a plurality of audio surveillance nodes, the sound data indicative of a sound detected by at least one of the audio surveillance nodes and an acoustic pulse received by a primary audio surveillance node and transmitted by a secondary audio surveillance node;

determining, by the control unit, a time-of-flight of the acoustic pulse;

determining, by the control unit, a location of the primary audio surveillance node based on the time-of-flight;

determining, by the control unit, a location of a source of the detected sound based on the sound data and based on the location of the primary audio surveillance node;

classifying, by the control unit, the detected sound based on the location of the source; and

controlling, by the control unit, a speaker to provide an audio response to the detected sound.

26. The method of claim 25 , wherein classifying the detected sound is based on a predefined alert condition, the predefined alert condition including a sound characteristic.

27. The method of claim 26 , further comprising altering the predefined alert condition based on a time of day.

28. The method of claim 26 , wherein the predefined alert condition includes a condition based on at least one of a voice, glass breaking, running, falling, a scream, fighting, or a gun shot.

29. The method of claim 26 , wherein the predefined alert condition is updated based on the detected sound.

30. The method of claim 26 , wherein the predefined alert condition is updated based on a user input received at a monitoring device.

31. The method of claim 25 , further comprising determining a movement of the source based on Doppler shifts in the detected sound.

32. The method of claim 25 , further comprising determining a velocity of the source based on the sound data.

33. The method of claim 25 , wherein the detected sound is detected by a microphone, and wherein the microphone is configured to detect sound only during a predefined time period.

34. The method of claim 33 , wherein the predefined time period occurs once per second.

35. The method of claim 25 , further comprising providing an audio response to the detected sound based on at least one of the classification of the detected sound or a user input received at a monitoring device.