Extraction of reverberant sound using microphone arrays

A non-transitory digital storage medium having stored thereon a computer program for performing a method for obtaining filter coefficients for a diffuse sound filter, the method comprising:

• defining a linear constraint for the filter coefficients of the diffuse sound filter, the linear constraint being based on a spatial coherence between a first diffuse sound portion in a first microphone signal and a second diffuse sound portion in a second microphone signal, the first microphone signal being captured by a first microphone and the second microphone signal being captured by a second microphone spaced apart from the first microphone;
• calculating at least one of a direction of arrival of at least one direct sound, signal statistics over the first and second microphone signals, and noise statistics over the first and second microphone signals;
• determining the filter coefficients of the diffuse sound filter by solving an optimization problem concerning at least one of the direction of arrival of the at least one direct sound, the signal statistics, and the noise statistics while considering the linear constraint for the filter coefficients;
• and
• using the filter coefficients within the diffuse sound filter for extracting a diffuse sound from or for suppressing a direct sound in a recording comprising the first microphone signal and the second microphone signal,
• when said computer program is run by a computer.

An apparatus for obtaining filter coefficients for a diffuse sound filter, the apparatus comprising:

• a linear constraint calculator configured to define a linear constraint for the filter coefficients of the diffuse sound filter, the linear constraint being based on a spatial coherence between a first diffuse sound portion in a first microphone signal and a second diffuse sound portion in a second microphone signal, the first microphone signal being captured by a first microphone and the second microphone signal being captured by a second microphone spaced apart from the first microphone;
• a calculator configured to calculate at least one of a direction of arrival of at least one direct sound, signal statistics over the first and second microphone signals, and noise statistics over the first and second microphone signals;
• and
• a filter coefficients calculator configured to determine the filter coefficients of the diffuse sound filter by solving an optimization problem concerning at least one of the direction of arrival of the at least one direct sound, the signal statistics, and the noise statistics while considering the linear constraint for the filter coefficients,
• wherein the apparatus is configured for using the filter coefficients within the diffuse sound filter for extracting a diffuse sound from or for suppressing a direct sound in a recording comprising the first microphone signal and the second microphone signal, and
• wherein one or more of the linear constraint calculator, the calculator, and the filter coefficients calculator is implemented, at least in part, by one or more hardware elements of the apparatus.