Position-robust multiple microphone noise estimation techniques
First Claim
1. A method for noise estimation and reduction in an audio signal, the method comprising:
- determining the power level difference (PLD) between a first microphone input signal and a second microphone input signal for a given time period by subtracting the absolute value of the second microphone input signal from the absolute value of the first microphone input signal, the PLD determination further comprising compensating for at least one of bias or mismatch between the first and second microphones, wherein a coherence value exists between the first and second microphone input signals, and an average coherence value is determined using coherence values for a plurality of frequency bins in the given time period;
determining if speech is detected in the first microphone input signal in the given time period, wherein speech is detected if the PLD between the first and second microphone input signals is a positive value, wherein speech is also detected if the PLD between the first and second microphone input signals is not a positive value but the average coherence value between the first and second microphone input signals is greater than or equal to a predetermined coherence value threshold, and wherein speech is not detected if the PLD between the first and second microphone input signals is not a positive value and the average coherence value between the first and second microphone input signals is less than the predetermined coherence value threshold;
calculating a noise power estimate based on whether speech is detected in the first microphone input signal in the given time period;
calculating a gain using the noise power estimate; and
performing noise reduction on the first microphone input signal using the gain to produce a speech signal that has reduced noise or is completely free of noise.
2 Assignments
0 Petitions
Accused Products
Abstract
Techniques are disclosed for position-robust multiple microphone noise estimation techniques. The position-robust noise estimation techniques can be used when receiving speech including diffuse noise sources, which is commonly encountered in noisy environments. The position-robust noise estimation techniques include detecting speech using the power level difference (PLD) and the coherence statistics (CS) between two microphone input signals. This multi-dimensional approach results in dual microphone noise estimation which is not affected by the position of the audio input device, resulting in more accurate detection of speech periods and more accurate noise estimation results. The position-robust noise estimate obtained from the techniques can then be used as part of a noise reduction system to reduce the levels of noise in noisy speech signals.
20 Citations
25 Claims
-
1. A method for noise estimation and reduction in an audio signal, the method comprising:
-
determining the power level difference (PLD) between a first microphone input signal and a second microphone input signal for a given time period by subtracting the absolute value of the second microphone input signal from the absolute value of the first microphone input signal, the PLD determination further comprising compensating for at least one of bias or mismatch between the first and second microphones, wherein a coherence value exists between the first and second microphone input signals, and an average coherence value is determined using coherence values for a plurality of frequency bins in the given time period; determining if speech is detected in the first microphone input signal in the given time period, wherein speech is detected if the PLD between the first and second microphone input signals is a positive value, wherein speech is also detected if the PLD between the first and second microphone input signals is not a positive value but the average coherence value between the first and second microphone input signals is greater than or equal to a predetermined coherence value threshold, and wherein speech is not detected if the PLD between the first and second microphone input signals is not a positive value and the average coherence value between the first and second microphone input signals is less than the predetermined coherence value threshold; calculating a noise power estimate based on whether speech is detected in the first microphone input signal in the given time period; calculating a gain using the noise power estimate; and performing noise reduction on the first microphone input signal using the gain to produce a speech signal that has reduced noise or is completely free of noise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A non-transitory computer program product having instructions encoded thereon that when executed by one or more processors cause a process to be carried out, the process comprising:
-
determine the power level difference (PLD) between a first microphone input signal and a second microphone input signal for a given time period by subtracting the absolute value of the second microphone input signal from the absolute value of the first microphone input signal, the PLD determination further comprising compensating for at least one of bias or mismatch between the first and second microphones, wherein a coherence value exists between the first and second microphone input signals, and an average coherence value is determined using coherence values for a plurality of frequency bins in the given time period; determine if speech is detected in the first microphone input signal in the given time period, wherein speech is detected if the PLD between the first and second microphone input signals is a positive value, wherein speech is also detected if the PLD between the first and second microphone input signals is not a positive value but the average coherence value between the first and second microphone input signals is greater than or equal to a predetermined coherence value threshold, and wherein speech is not detected if the PLD between the first and second microphone input signals is not a positive value and the average coherence value between the first and second microphone input signals is less than the predetermined coherence value threshold; calculate a noise power estimate based on whether speech is detected in the first microphone input signal in the given time period; calculate a gain using the noise power estimate; and perform noise reduction on the first microphone input signal using the gain to produce a speech signal that has reduced noise or is completely free of noise. - View Dependent Claims (15, 16, 17, 18, 19)
-
-
20. A system for noise estimation and reduction, the system comprising:
-
a first microphone configured to receive a first microphone input signal; a second microphone configured to receive a second microphone input signal; and at least one processor configured to; determine the power level difference (PLD) between a first microphone input signal and a second microphone input signal for a given time period by subtracting the absolute value of the second microphone input signal from the absolute value of the first microphone input signal, the PLD determination further comprising compensating for at least one of bias or mismatch between the first and second microphones, wherein a coherence value exists between the first and second microphone input signals, and an average coherence value is determined using coherence values for a plurality of frequency bins in the given time period; determine if speech is detected in the first microphone input signal in the given time period, wherein speech is detected if the PLD between the first and second microphone input signals is a positive value, wherein speech is also detected if the PLD between the first and second microphone input signals is not a positive value but the average coherence value between the first and second microphone input signals is greater than or equal to a predetermined coherence value threshold, and wherein speech is not detected if the PLD between the first and second microphone input signals is not a positive value and the average coherence value between the first and second microphone input signals is less than the predetermined coherence value threshold; calculate a noise power estimate based on whether speech is detected in the first microphone input signal in the given time period; calculate a gain using the noise power estimate; and perform noise reduction on the first microphone input signal using the gain to produce a speech signal that has reduced noise or is completely free of noise. - View Dependent Claims (21, 22, 23, 24, 25)
-
Specification