Signal expander with discrimination between close and distant acoustic source

A method of discriminating between signals produced by a desired acoustic source and an undesired acoustic source, comprising:

• using a first microphone disposed at a distance from the desired acoustic source;
• using a second microphone disposed at a second distance from the desired acoustic source;
• utilizing signals from the first microphone and second microphone to produce an output signal representing an estimate of the proximity of the desired acoustic source based upon a ratio of signals produced by the first microphone and the second microphone;
• and
• adjusting the gain of the signal from at least one of the first and second microphones by utilizing the estimate of the proximity of the desired acoustic source.

An apparatus for discriminating between signals produced by a desired acoustic source and an undesired acoustic source, the apparatus comprising:

• an input block including a first microphone disposed at a first distance from the desired acoustic source and a second microphone disposed at a second distance from the desired acoustic source;
• a proximity estimation block coupled to the input block and configured to produce an estimate of the proximity of the desired acoustic source based upon output signals of the microphones;
• a speech activity detector coupled to the proximity estimation block and configured to produce a control signal in response to the estimate of the proximity;
• a differential amplifier having inputs coupled to the first microphone and the second microphone and having an output;
• a variable gain block coupled to the output of the differential amplifier and the proximity estimation block, and configured to adjust the gain of the output signal from the differential amplifier based upon the estimate of the proximity;
• and
• a microphone adjustment stage coupled to each of the microphones, the microphone adjustment stage permitting the sensitivities of the microphones to be adjusted and substantially matched.

An apparatus for discriminating between signals produced by a desired acoustic source and an undesired acoustic source, the apparatus comprising:

• a first microphone disposed at a first distance from the desired acoustic source;
• at least a second microphone disposed at a second distance from the desired acoustic source;
• a proximity estimation block configured to utilize signals from the first microphone and second microphone to produce a signal representing an estimate of the proximity of the desired acoustic source;
• a variable gain block configured to adjust the gain of an output signal from at least one of the microphones by utilizing the estimate of the proximity of the desired acoustic source;
• and
• a speech activity detector coupled to the proximity estimation block and to the variable gain block, and configured to indicate the presence of desired signals from the desired acoustic source.

An apparatus for discriminating between signals produced by a desired acoustic source and an undesired acoustic source, the apparatus comprising:

• an input block including a first microphone disposed at a first distance from the desired acoustic source and a second microphone disposed at a second distance from the desired acoustic source;
• a proximity estimation block coupled to the input block and configured to produce an estimate of the proximity of the desired acoustic source based upon output signals of the microphones;
• a speech activity detector coupled to the proximity estimation block and configured to produce a control signal in response to the estimate of the proximity;
• and
• a variable gain block coupled to the input block and the speech activity detector, and configured to adjust the gain of the output signal from at least one of the microphones based upon the estimate of the proximity.

An apparatus for discriminating between signals produced by a desired acoustic source and an undesired acoustic source, the apparatus comprising:

• a first microphone disposed at a first distance from the desired acoustic source;
• at least a second microphone disposed at a second distance from the desired acoustic source;
• a proximity estimation block configured to utilize signals from the first microphone and second microphone to produce a signal representing an estimate of the proximity of the desired acoustic source;
• and
• a variable gain block configured to adjust the gain of an output signal from at least one of the microphones by utilizing the estimate of the proximity of the desired acoustic source, wherein the gain applied to the output signal from the first microphone is determined by both the level of output signal and by the estimate of the proximity exceeding a threshold value.

A method of discriminating between signals produced by a desired acoustic source and an undesired acoustic source, comprising:

• using a first microphone disposed at a distance from the desired acoustic source;
• using a second microphone disposed at a second distance from the desired acoustic source;
• utilizing signals from the first microphone and second microphone to produce an output signal representing an estimate of the proximity of the desired acoustic source;
• and
• adjusting the gain of the signal from at least one of the first and second microphones by utilizing the estimate of the proximity of the desired acoustic source wherein the gain applied to the signal from the first microphone is determined by a level of the signal and by the estimate of the proximity exceeding a threshold value.

An apparatus for discriminating between signals produced by a desired acoustic source and an undesired acoustic source, the apparatus comprising:

• an input block including a first microphone disposed at a first distance from the desired acoustic source and a second microphone disposed at a second distance from the desired acoustic source;
• a proximity estimation block coupled to the input block and configured to produce an estimate of the proximity of the desired acoustic source based upon output signals of the microphones;
• a speech activity detector coupled to the proximity estimation block and configured to produce a control signal in response to the estimate of the proximity;
• and
• a variable gain block coupled to the input block and the proximity estimation block, and configured to adjust the gain of the output signal from at least one of the microphones based upon the estimate of the proximity.

A method of discriminating between signals produced by a desired acoustic source and at least one undesired acoustic source, the method comprising:

• using a first microphone disposed at a distance from the desired acoustic source;
• using a second microphone disposed at a greater distance from the desired acoustic source and bearing a known relationship to the first microphone;
• adjusting sensitivities of the first and second microphones to be substantially matched;
• utilizing the output signals from the first microphone and the second microphone to produce a signal representing an estimate of the proximity of the desired acoustic source in an active state;
• producing an output based on the difference between the instantaneous values of the output signals from the first microphone and the second microphone in order to produce a composite output with the properties of a directional microphone;
• and
• adjusting a gain of the output based on the difference between the instantaneous values of the output signals from the first microphone and the second microphone by use of the estimate of the proximity of the desired acoustic source.

An apparatus for discriminating between signals produced by a desired acoustic source and an undesired acoustic source, comprising:

• a first microphone disposed at a distance from the desired acoustic source;
• a second microphone disposed at a second distance from the desired acoustic source;
• means, coupled to the first microphone and second microphone, for utilizing signals from the first microphone and second microphone to produce an output signal representing an estimate of the proximity of the desired acoustic source based upon a ratio of signals produced by the first microphone and the second microphone;
• and
• means, coupled to the utilizing means, for adjusting the gain of the signal from at least one of the first and second microphones by utilizing the estimate of the proximity of the desired acoustic source.

An apparatus for discriminating between signals produced by a desired acoustic source and at least one undesired acoustic source, the method comprising:

• a first microphone disposed at a distance from the desired acoustic source;
• a second microphone disposed at a greater distance from the desired acoustic source and bearing a known relationship to the first microphone;
• means, coupled to the first microphone and second microphone, for utilizing the output signals from the first microphone and the second microphone to produce a signal representing an estimate of the proximity of the desired acoustic source in an active state;
• means, coupled to each of the microphones, for permitting sensitivities of the microphones to be adjusted and substantially matched;
• means, coupled to the first microphone and second microphone, for producing an output based on the difference between the instantaneous values of the output signals from the first microphone and the second microphone in order to produce a composite output with the properties of a directional microphone;
• means, coupled to the utilizing means, for adjusting a gain of the output based on the difference between the instantaneous values of the output signals from the first microphone and the second microphone by use of the estimate of the proximity of the desired acoustic source.