SIGNAL PROCESSING SYSTEM AND METHODS FOR RELIABLY DETECTING AUDIBLE ALARMS

• US 20110025499A1
• Filed: 04/08/2010
• Published: 02/03/2011
• Est. Priority Date: 07/29/2009
• Status: Active Grant

• Current Assignee: InnovAlarm Corporation
• Original Assignee: InnovAlarm Corporation
• Inventors: ALBERT, David E., HOY, Leslie D., LEWIS, James J., SMITH, Landgrave T.
• Granted Patent: US 8,269,625 B2
• Time in Patent Office: Days
• US Class Current: 340/540
• CPC Class Codes: G08B 1/08 using electric transmission ; transformation of alarm signals to electrical signals from a different medium, e.g. transmission of an electric alarm signal upon detection of an audible alarm signal
• CPC Class Codes: G08B 13/1672 using sonic detecting means, e.g. a microphone operating in the audio frequency range
• CPC Class Codes: G08B 29/185 Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system
• CPC Class Codes: G08B 3/10 using electric transmission; using electromagnetic transmission
• CPC Class Codes: G08B 7/06 using electric transmission , e.g. involving audible and visible signalling through the use of sound and light sources
• CPC Class Codes: H04R 29/00 Monitoring arrangements; Testing arrangements for hearing aids H04R25/30; detection of loudspeaker connection H04R5/04; sound-field adaptation dependent on speaker detection H04S7/308

Abstract

A signal processing system and associated methods are disclosed for reliably detecting audible alert signals, such as Temporal-3 (or Code-3) and Temporal-4 (or Code-4) alert signals generated by commercially available smoke, fire, and carbon monoxide detectors. The system and methods are capable of detecting audible alert signals of different intensities in the presence of dynamic background environment (e.g., television programming, music, noise, and the like). The system and methods are capable of detecting audible alert signals generated by far away smoke, fire, and carbon monoxide detectors. The signal processing system and methods may, in some embodiments, be incorporated into a bedside or other unit that generates a supplemental alert signal capable of alerting individuals who might not otherwise respond to the alarm condition, such as individuals who are asleep, children, hearing impaired, or intoxicated.

Claims

1. A method for detecting audible alert signals implemented in signal processing circuitry, the method comprising:

generating a digital representation of a received audio signal;

for each plurality of templates, comparing the digital representation of the received audio signal to the respective template, and generating a matching score representing a degree of match between the digital representation of the received audio signal and the respective template, wherein each template corresponds to an acceptable audible alert signal timing pattern, and the plurality of templates encompass an acceptable range of variation in a timing pattern of a standard audible alert signal; and

determining, based at least partly on the matching scores corresponding to the plurality of templates, whether an audible alert signal is present.

2. The method of claim 1, wherein the plurality of templates comprises templates that correspond to variations in a Temporal-3 timing pattern.

3. The method of claim 1, wherein the plurality of templates comprises templates that correspond to variations in a Temporal-4 timing pattern

4. The method of claim 1, wherein the plurality of templates includes at least ten templates.

5. The method of claim 1, wherein generating the digital representations comprises applying band pass filtering such that the digital representation corresponds to a frequency band falling within a range of acceptable frequencies of an audible alert signal.

6. The method of claim 5, further comprising repeating the generating and comparing steps for each of multiple additional frequency bands falling within the range, to thereby generate a separate set of matching scores for each of a plurality of frequency ranges, and wherein said determining step comprises analyzing each of the sets of matching scores.

7. The method of claim 6, wherein the number of the frequency bands is at least ten.

8. The method of claim 6, wherein the number of the frequency bands is at least twenty.

9. The method of claim 6, wherein each of the plurality of frequency ranges falls within the range of 2.9 kHz to 3.5 kHz.

10. The method of claim 1, further comprising:

estimating a noise content of the received audio signal; and

determining, based at least partly on the noise content, whether an audible alert signal is present.

11. A computer-readable medium which stores executable instructions capable of causing a computing device to perform a signal processing method that comprises:

generating a digital representation of a received audio signal;

for each plurality of templates, comparing the digital representation of the received audio signal to the respective template, and generating a matching score representing a degree of match between the digital representation of the received audio signal and the respective template, wherein each template corresponds to an acceptable audible alert signal timing pattern, and the plurality of templates encompass an acceptable range of variation in a timing pattern of a standard audible alert signal; and

determining, based at least partly on the matching scores corresponding to the plurality of templates, whether an audible alert signal is present.

12. The computer-readable medium of claim 11, wherein the plurality of templates comprises templates that correspond to variations in a Temporal-3 timing pattern.

13. The computer-readable medium of claim 11, wherein the plurality of templates comprises templates that correspond to variations in a Temporal-4 timing pattern.

14. The method of claim 11, wherein the plurality of templates includes at least ten templates.

15. A signal processing system for detecting audible alert signals comprising:

a circuit configured to receive an audio signal and to generate a digital representation of the received audio signal;

a memory buffer configured to store a plurality of templates, wherein each template corresponds to an acceptable audible alert signal timing pattern, and the plurality of templates encompass an acceptable range of variation in a timing pattern of a standard audible alert signal; and

a circuit configured to;

compare the digital representation of the received audio signal to the respective template;

generate a matching score representing a degree of match between the digital representation of the received audio signal and the respective template, and

determine, based at least partly on the matching scores corresponding to the plurality of templates, whether an audible alert signal is present.

16. The signal processing system of claim 15, wherein the plurality of templates comprises templates that correspond to variations in a Temporal-3 timing pattern.

17. The signal processing system of claim 15, wherein the plurality of templates comprises templates that correspond to variations in a Temporal-4 timing pattern.

18. The method of claim 15, wherein the number of the frequency bands is twenty-one.

19. The signal processing system of claim 15, further comprising a supplemental alert generator configured to generate a supplemental alert signal in response to the determination that an audible alert signal is present.

20. The signal processing system of claim 19, wherein the supplemental alert signal is a low-frequency square wave sound pattern.