System and method for detection of aural signals

A method of warning a person of a condition by detecting a sound indicative that the condition exists comprising:

• receiving an audio frequency signal indicative of the condition, the frequency signal being in one of a band of audio frequencies, and the receiving means also receiving other audio frequency signals;
• processing all received audio frequency signals including converting the received audio frequency signals to digital signals, sampling the digital signal at a predetermined rate, scaling the resulting samples as a function of an average energy value, transforming the scaled samples into a transform covering a range of audio frequencies within the band of frequencies, and performing an autocorrelation on the resulting transform to ascertain if the received audio frequency signal represents a sound for which a warning should issue;
• comparing the autocorrelation with a set of criteria representing an audio frequency signal to determine if an audio frequency signal representing the condition has been received and,
• providing a visible signal to the person that the condition exists so the person can take action appropriate with regard to the condition when the processing indicates the sound detected signals the presence of the condition for which action should be taken.

An early warning system for visually informing the hearing impaired driver of an automotive vehicle of the proximity of an emergency vehicle by detecting a siren being sounded by the emergency vehicle comprising:

• means for receiving an audio frequency signal transmitted by the siren, the frequency signal being in one of a band of frequencies, and the receiving means also receiving other radio frequency signals;
• signal processing means for processing all received audio frequency signals, said processing means including means for converting the received audio frequency signals to digital signals, and sampling the digital signals at a predetermined rate, scaling the resulting sample as a function of an average signal energy value, transforming the scaled samples into a transform covering a range of audio frequencies with the band of frequencies, and means performing an autocorrelation of the resulting, transform and comparing the results thereof to predetermined set of criteria representing the sounds made by various sirens;
• and,
• visual indication means for providing a visible signal to the driver of the proximity of an emergency vehicle so the driver can take appropriate action to avoid the emergency vehicle, the signal processing means illuminating the visual indication means when the comparison indicates a received signal corresponds with the sound made by an emergency vehicle siren.

A system responsive to a warning siren of an emergency vehicle approaching an intersection controlled by a traffic signal and a traffic signal controller for pre-empting the traffic signal so as to insure that the emergency vehicle has the right of way through the intersection and to insure that cross traffic is stopped, said system comprising:

• one or more sensing units for monitoring audio signals at the intersection;
• processing means for processing all of the audio signals monitored by said sensing units, said signal processing means including means for converting the monitored audio signals to digital signals, sampling the digital signals at a predetermined rate, scaling the resulting samples as a function of an average signal energy value, and for transforming the scaled samples into a transform covering a range of audio frequencies;
• means for storing one or more predetermined audio signals corresponding to the audio signal emitted by an emergency vehicle siren;
• means for determining if said digital signals from said sensing units correlate to one of said predetermined audio signals from an emergency vehicle siren;
• means for generating an output signal responsive to a determination that an emergency vehicle is approaching the intersection while sounding its siren;
• and
• means responsive to said output signal for pre-empting said traffic signal controller so as to insure that said traffic signal allows said emergency vehicle the right of way through said intersection and stops cross traffic.

A method of pre-empting a traffic signal at an intersection controlled by a traffic signal controller in response to an audio warning siren signal emitted by an emergency vehicle approaching the traffic signal so as to insure that the emergency vehicle has the right of way through the intersection and that cross traffic is stopped, said method comprising:

• monitoring audio signals at the intersection:
• processing said audio signals received at the intersection including converting said audio signals to digital signals, sampling the digital signals at a predetermined rate, scaling the resulting signals as a function of an average signal energy value, and transforming the scaled samples into a transform covering a range of audio frequencies;
• comparing said transform of said audio signals received at the intersection to one or more predetermined signals corresponding to the audio signal emitted by an emergency vehicle siren;
• generating a signal in response to determining that the audio signal being received from said intersection corresponds to said predetermined emergency vehicle siren signal;
• and
• pre-empting the control of said traffic signal so as to insure that said emergency vehicle has the right of way through the intersection and that cross traffic is stopped.

A method of warning the hearing impaired driver of an automotive vehicle of the proximity of an emergency vehicle by detecting a siren being sounded by the emergency vehicle comprising:

• receiving an audio frequency signal transmitted by the siren, the frequency signal being in one of a band of audio frequencies, and the receiving means also receiving other audio frequency signals;
• processing all of the received audio frequency signals including converting the received audio frequency signals to digital signals, sampling the digital signals at a predetermined sample rate, scaling the samples based on an average signal energy value, calculating a discrete Fourier Transform from the scaled sample information, the Fourier transform covering a plurality of spectral bands in the audio frequency and performing an autocorrelation on the result of the calculated transform to ascertain if a received audio frequency signal represents the sound made by a siren;
• comparing the autocorrelation with a set of criteria representing audio frequency signals for sirens to determine if a siren sound has been received;
• and,
• illuminating a light to provide a visible signal to the driver of the proximity of an emergency vehicle so the driver can take appropriate action to avoid the emergency vehicle, when the processing indicates the sound was made by an emergency vehicle siren.