SPEECH DISTRIBUTION SYSTEM
First Claim
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1. A method of distributing speech in the presence of an audio system and using a single microphone (18.1) which includes the steps of:
- (a) at a first location receiving a first audio signal (S1a) through a single microphone (18.1), the first audio signal including a second signal related to an output of the audio system, a voice signal representing speech originating from or near the first location, and noise (AS1m), (b) extracting from the first audio signal a third signal (S1ae1), representing the voice signal and the noise, by subtracting from the first audio signal an estimation of the second signal, determined by using an electrical output signal (Ase) of the audio system on its own as a reference signal for an adaptive filter, (52), the third signal being extracted directly from the first audio signal and without going through a loudspeaker and microphone first, (c) amplifying the third signal and then mixing the third signal (S1ae1) with the electrical output signal (Ase) to produce a combined output signal, (d) distributing the combined output signal through the audio system to at least one loudspeaker (12.2 to 12.4), said method further including at least one of the following steps;
(i) automatically adjusting the level of amplification of the third signal in step (c) based on at least the level of background noise;
(ii) individually adjusting the level of amplification of the third signal in step (c) for each loudspeaker;
(iii) reducing the third signal in step (c) if it is determined that no speech is present in the first audio signal (S1a), and (iv) using the combined output(s) as reference input(s) to an adaptive echo cancellation mechanism (54) to reduce acoustic feedback.
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Abstract
A method of distributing speech which includes the steps of, at a given location, receiving an audio signal, extracting from the audio signal a signal representing speech originating from or near the location, and distributing an electric signal which is mixed with the extracted speech signal via an audio system to be played over at least one loudspeaker.
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Citations
33 Claims
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1. A method of distributing speech in the presence of an audio system and using a single microphone (18.1) which includes the steps of:
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(a) at a first location receiving a first audio signal (S1a) through a single microphone (18.1), the first audio signal including a second signal related to an output of the audio system, a voice signal representing speech originating from or near the first location, and noise (AS1m), (b) extracting from the first audio signal a third signal (S1ae1), representing the voice signal and the noise, by subtracting from the first audio signal an estimation of the second signal, determined by using an electrical output signal (Ase) of the audio system on its own as a reference signal for an adaptive filter, (52), the third signal being extracted directly from the first audio signal and without going through a loudspeaker and microphone first, (c) amplifying the third signal and then mixing the third signal (S1ae1) with the electrical output signal (Ase) to produce a combined output signal, (d) distributing the combined output signal through the audio system to at least one loudspeaker (12.2 to 12.4), said method further including at least one of the following steps;
(i) automatically adjusting the level of amplification of the third signal in step (c) based on at least the level of background noise;
(ii) individually adjusting the level of amplification of the third signal in step (c) for each loudspeaker;
(iii) reducing the third signal in step (c) if it is determined that no speech is present in the first audio signal (S1a), and (iv) using the combined output(s) as reference input(s) to an adaptive echo cancellation mechanism (54) to reduce acoustic feedback. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for distributing speech in the presence of a first audio signal (As) produced by an audio system (10), the apparatus comprising
a receiving device (18.1) for receiving an acoustic signal (S1a, As1m) from at least one of a plurality of locations, the acoustic signal including at least a second signal related to an output signal of the audio system, a voice signal (S1a) representing speech originating at least from or near the one location and noise, a module (1.1) for extracting from the received acoustic signal a third signal which represents the voice signal and the noise, by subtracting from the received acoustic signal an estimation of the second signal which is calculated using an electrical output signal of the audio system without mixing it with other signals as reference signal to an adaptive filter and the received acoustic signal, the third signal being extracted directly from the first audio signal and without going through a loudspeaker and microphone first, and the apparatus further comprising at least one of the following configurations (i) a distribution unit (14, 16.2 to 16.4) for distributing a combined output signal, which includes the extracted voice signal and the first audio signal, to at least some of the locations, the third signal being amplified to a level that is at least influenced by the level of background noise, (ii) a distribution unit (14, 16.2 to 16.4) for distributing a combined output signal, which includes the extracted voice signal and the first audio signal, to an input to a mobile phone, (iii) at least one adaptive filter, with coefficients for the adaptive filter(s) determined during an installation or setup procedure and then stored in memory for use when the filter is activated, (iv) an adaptive echo cancellation filter (54) receiving the electrical signals going to the loudspeakers for reducing acoustic feedback.
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26. A method of distributing speech in the presence of an audio system which comprises the steps of:
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(a) receiving at least one first location a first audio signal (S1a) through a microphone (18.1, 18.2, 18.3, 18.4), the first audio signal including a second signal related to an output of said audio system, a voice signal representing speech origination from or near at least one of the first locations and background noise (AS1m), (b) extracting from the first audio signal (S1a) a third signal (S1ae1), representing the voice signal and the noise, by subtracting from the first audio signal an estimation of the second signal, determined by using an electrical output signal (Ase) of the audio system as a reference signal for an adaptive filter, (52) the third signal being extracted directly from the first audio signal and without going through a loudspeaker and microphone first, (c) mixing the third signal (S1ae1) with the electrical output signal (Ase) to produce a combined output signal, (d) distributing the combined output signal through the audio system to at least one loudspeaker (12.2 to 12.4), said method further including at least one of the following steps;
(i) monitoring the background noise and automatically adjusting the amplification of the speech signal to reflect variations in the level of the background noise, (ii) applying delays, corresponding to the distance between the microphone(s) and the loudspeaker(s) based on the speed of sound, to the distribution of the third signal, (iii) routing the third signal extracted from a first audio signal associated with a specific location to a vehicle based mobile phone input and routing the output from the mobile phone to the loudspeaker of the same specific location, and (iv) reducing acoustic feedback through adaptive echo cancellation (54) based on the electrical signals going to the loudspeakers being used as an input to an adaptive echo canceller. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33)
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Specification