Pole-zero blocking matrix for low-delay far-field beamforming

A method for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• providing the first microphone signal as input to a first adaptive finite impulse response (FIR) filter;
• delaying the second microphone signal by a predetermined delay amount;
• providing the delayed second microphone signal as input to a second adaptive FIR filter;
• applying a linear constraint to coefficients of the first and second adaptive FIR filters;
• and
• jointly adapting the first and second adaptive FIR filters to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• wherein the ABM inter-microphone transfer function is modeled and estimated by the method with low delay by using a pole-zero representation or IIR filter to exploit a noncausal relationship inherent in the first and second microphone signals.

A system for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• a first adaptive finite impulse response (FIR) filter to which the first microphone signal is provided as input;
• a delay element that delays the second microphone signal by a predetermined delay amount;
• and
• a second adaptive FIR filter to which the delayed second microphone signal is provided as input;
• wherein a linear constraint is applied to coefficients of the first and second adaptive FIR filters;
• wherein the first and second adaptive FIR filters are jointly adapted to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• wherein, depending on the linear constraint applied to the coefficients of the first and second adaptive FIR filters, the predetermined delay amount may be zero.

A system for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• a first adaptive finite impulse response (FIR) filter to which the first microphone signal is provided as input;
• a delay element that delays the second microphone signal by a predetermined delay amount;
• and
• a second adaptive FIR filter to which the delayed second microphone signal is provided as input;
• wherein a linear constraint is applied to coefficients of the first and second adaptive FIR filters;
• wherein the first and second adaptive FIR filters are jointly adapted to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• wherein applying the linear constraint to coefficients of the first and second adaptive FIR filters comprises:
• constraining a first coefficient of the second adaptive FIR filter to a fixed non-zero value.

A system for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• a first adaptive finite impulse response (FIR) filter to which the first microphone signal is provided as input;
• a delay element that delays the second microphone signal by a predetermined delay amount;
• a second adaptive FIR filter to which the delayed second microphone signal is provided as input;
• wherein a linear constraint is applied to coefficients of the first and second adaptive FIR filters;
• wherein the first and second adaptive FIR filters are jointly adapted to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• one or more additional microphones that output respective additional microphone signals;
• wherein for each additional microphone of the one or more additional microphones, the system further comprises:
• a first adaptive FIR filter to which the first microphone signal is provided as input;
• a delay element that delays the respective additional microphone signal by a predetermined delay amount;
• and
• a second adaptive FIR filter to which the delayed respective additional microphone signal is provided as input;
• wherein a linear constraint is applied to coefficients of the first and second adaptive FIR filters;
• and
• wherein the first and second adaptive FIR filters are jointly adapted to minimize an additional error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• wherein the additional error signals are included as noise references in an adaptive noise canceller of a beamformer.

A method for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• providing the first microphone signal as input to a first adaptive finite impulse response (FIR) filter;
• delaying the second microphone signal by a predetermined delay amount;
• providing the delayed second microphone signal as input to a second adaptive FIR filter;
• applying a linear constraint to coefficients of the first and second adaptive FIR filters;
• jointly adapting the first and second adaptive FIR filters to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• wherein, depending on the linear constraint applied to the coefficients of the first and second adaptive FIR filters, the predetermined delay amount may be zero.

A method for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• providing the first microphone signal as input to a first adaptive finite impulse response (FIR) filter;
• delaying the second microphone signal by a predetermined delay amount;
• providing the delayed second microphone signal as input to a second adaptive FIR filter;
• applying a linear constraint to coefficients of the first and second adaptive FIR filters;
• jointly adapting the first and second adaptive FIR filters to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• wherein said applying the linear constraint to coefficients of the first and second adaptive FIR filters comprises:
• constraining a first coefficient of the second adaptive FIR filter to a fixed non-zero value.

A method for pole-zero or infinite impulse response (IIR) modeling and estimation of an adaptive blocking matrix (ABM) inter-microphone transfer function between first and second microphones that output respective first and second microphone signals, comprising:

• providing the first microphone signal as input to a first adaptive finite impulse response (FIR) filter;
• delaying the second microphone signal by a predetermined delay amount;
• providing the delayed second microphone signal as input to a second adaptive FIR filter;
• applying a linear constraint to coefficients of the first and second adaptive FIR filters;
• jointly adapting the first and second adaptive FIR filters to minimize an error signal that is a difference of outputs of the first and second adaptive FIR filters;
• for each additional microphone of one or more additional microphones that output respective additional microphone signals:
• providing the first microphone signal to a first adaptive FIR filter;
• delaying the respective additional microphone signal by a predetermined delay amount;
• providing the delayed respective additional microphone signal as input to a second adaptive FIR filter;
• applying a linear constraint to coefficients of the first and second adaptive FIR filters;
• and
• jointly adapting the first and second adaptive FIR filters to minimize an additional error signal that is a difference of outputs of the first and second adaptive FIR filters;
• and
• including the additional error signals as noise references in an adaptive noise canceller of a beamformer.