SIGNAL PROCESSING SYSTEM AND METHODS FOR RELIABLY DETECTING AUDIBLE ALARMS
A signal processing system and associated methods are disclosed for reliably detecting audible alert signals, such as Temporal-3 and Temporal-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 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 audible alert signal, such as individuals who are asleep, hearing impaired, or intoxicated.
1 . A method for detecting audible alert signals, the method comprising:
generating a digital representation of a received audio signal;
accessing a plurality of templates stored in a memory, each template corresponding to a respective audible alert signal timing pattern, said plurality of templates encompassing an acceptable range of timing pattern variations;
generating, by signal processing circuitry, a plurality of matching scores, each of which represents a degree of match between the digital representation of the received audio signal and a respective template; and
determining, based at least partly on the matching scores, 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 representation 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 , wherein the method comprises generating a set of matching scores for each of multiple respective frequency bands falling within the range of acceptable frequencies, and wherein determining whether an audible alert signal is present comprises analyzing each of the sets of matching scores.
7 . The method of claim 1 , wherein the plurality of templates encompass acceptable variations in at least the following audible alert signal parameters: signal period, beeping tone duration, silence interval duration, and signal intensity.
8 . The method of claim 1 , wherein each template corresponds to an acceptable audible alert timing pattern.
9 . The method of claim 1 , wherein at least some of the templates include don't care values corresponding to points in time at which a state of the digital representation of the received audio signal does not influence the corresponding matching score.
10 . The method of claim 1 , wherein determining whether an audible alert signal is present comprises determining whether the plurality of matching scores follow a pattern associated with a valid Temporal-3 alert signal.
11 . A computer-readable medium having stored thereon executable code that directs a processor to perform a process that comprises:
accessing a digital representation of a received audio signal;
accessing a plurality of templates stored in a memory, each template corresponding to a respective audible alert signal timing pattern, said plurality of templates encompassing an acceptable range of timing pattern variations;
generating a plurality of matching scores, each matching score representing a degree of match between the digital representation of the received audio signal and a respective template; and
determining, based at least partly on the matching scores, 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 at least one of: a Temporal-3 timing pattern, and a Temporal-4 timing pattern
13 . The computer-readable medium of claim 11 , wherein the plurality of templates includes at least ten templates.
14 . The computer-readable medium of claim 11 , wherein generating the digital representation 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.
15 . The computer-readable medium of claim 11 , wherein the method comprises generating a set of matching scores for each of multiple respective frequency bands falling within a range of acceptable frequencies, and wherein determining whether an audible alert signal is present comprises analyzing each of the sets of matching scores.
16 . The computer-readable medium of claim 11 , wherein the plurality of templates encompass acceptable variations in at least the following audible alert signal parameters: signal period, beeping tone duration, and silence interval duration.
17 . The computer-readable medium of claim 11 , wherein determining whether an audible alert signal is present comprises determining whether the plurality of matching scores follow a pattern associated with a valid Temporal-3 alert signal.
18 . A system for detecting audible alert signals, comprising:
a memory that stores data representing a plurality of signal patterns, each of which represents a valid signal pattern for an audible alert signal, said plurality of signal patterns encompassing a range of signal pattern variations; and
signal processing circuitry configured to receive a digital representation of an audio signal, and to use the data representing the plurality of signal patterns to generate, for each valid signal pattern, a respective matching score that represents a degree to which the digital representation of the audio signal matches the respective valid signal pattern, said signal processing circuitry additionally configured to use the matching scores to determine whether the audio signal is an audible alert signal.
19 . The system of claim 18 , wherein the plurality of signal patterns include a plurality of variations of a Temporal-3 signal pattern.
20 . The system of claim 19 , wherein the signal processing circuitry is configured to determine whether the matching scores follow a pattern associated with a valid Temporal-3 alert signal.
21 . The system of claim 18 , wherein the plurality of signal patterns include a plurality of variations of a Temporal-4 signal pattern.
22 . The system of claim 18 , wherein the signal processing circuitry is additionally configured to:
generate a respective set of matching scores for each of a plurality of digital representations of the audio signal, each digital representation corresponding to a different frequency band; and
use the sets of matching scores in combination to determine whether an audible alert is present.
23 . The system of claim 18 , wherein the plurality of signal patterns encompass variations in at least the following audible alert signal parameters: signal period, beeping tone duration, and silence interval duration.
24 . The system of claim 18 , wherein the signal processing circuitry comprises a microcontroller.