# US 2014/0193000 A1 · Method and apparatus for generating a noise reduced audio signal using a microphone array

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- Number: US 2014/0193000 A1
- Document ID: US20140193000A1
- Status: Published application
- Kind: A1
- Application number: 14/148,230
- Filed: 2014-01-06
- Published: 2014-07-10
- Earliest claimed: 2013-01-07
- Inventors: Dietmar RUWISCH
- Web page: https://patentgrep.com/patent/US20140193000A1

## CPC

- G10L 21/0264: characterised by the type of parameter measurement, e.g. correlation techniques, zero crossing techniques or predictive techniques
- G10L 21/0232: Processing in the frequency domain
- G10L 2021/02166: {Microphone arrays; Beamforming}
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## Abstract

A method and apparatus for generating a noise reduced output signal from sound received by a first and second microphone arranged as a microphone array. The method includes transforming sound received by the first microphone into a first input signal and sound received by a second microphone into a second input signal and calculating, for each of the frequency components, a weighted sum of at least two intermediate signals calculated from the input signals by means of complex valued transfer functions and real valued Equalizer functions. The method includes a weighing function with range between zero and one, with quotients of signal energies of the intermediate functions as arguments of the weighing function, and generating the noise reduced output signal based on the weighted sum of the intermediate functions and based on the weighted sum of the first and second intermediate function at each of the frequency components.

## Claims

### Claim 1

A method for generating a noise reduced output signal from sound received by a first and second microphone arranged as microphone array, said method comprising:
transforming said sound received by said first microphone into a first input signal,
wherein said first input signal is a frequency domain signal of an analog-to-digital converted audio signal corresponding to said sound received by said first microphone;
transforming sound received by a second microphone into a second input signal,
wherein said second input signal is a frequency domain signal of an analog-to-digital converted audio signal corresponding to the sound received by said second microphone;
calculating, for each of the plurality of frequency components, a weighted sum of at least two intermediate signals that are calculated from the input signals by means of at least one complex valued transfer functions and at least one real valued Equalizer functions,
said weighted sum having a weighing function with range between zero and one, with signal energy quotients of said intermediate functions as argument of said weighing function; and
generating said noise reduced output signal based on said weighted sum of said first and said second intermediate function at each of said plurality of frequency components.

### Claim 2

An apparatus for generating a noise reduced output signal from sound received by a first and second microphone arranged as microphone array, said apparatus comprises means for:
transforming said sound received by said first microphone into a first input signal,
wherein said first input signal is a frequency domain signal of an analog-to-digital converted audio signal corresponding to said sound received by said first microphone;
transforming sound received by a second microphone into a second input signal,
wherein said second input signal is a frequency domain signal of an analog-to-digital converted audio signal corresponding to the sound received by said second microphone;
calculating, for each of the plurality of frequency components, a weighted sum of at least two intermediate signals that are calculated from the input signals by means of at least one complex valued transfer functions and at least one real valued Equalizer functions,
said weighted sum having a weighing function with range between zero and one, with signal energy quotients of said intermediate functions as argument of said weighing function; and
generating said noise reduced output signal based on said weighted sum of said first and said second intermediate function at each of said plurality of frequency components.

### Claim 3

A computer program product comprising a physical computer readable storage medium containing computer executable program code for generating a noise reduced output signal from sound received by a first and second microphone arranged as microphone array, said computer executable code comprising:
a code portion for transforming said sound received by said first microphone into a first input signal,
wherein said first input signal is a frequency domain signal of an analog-to-digital converted audio signal corresponding to said sound received by said first microphone;
a code portion for transforming sound received by a second microphone into a second input signal,
wherein said second input signal is a frequency domain signal of an analog-to-digital converted audio signal corresponding to the sound received by said second microphone;
a code portion for calculating, for each of the plurality of frequency components, a weighted sum of at least two intermediate signals that are calculated from the input signals by means of at least one complex valued transfer functions and at least one real valued Equalizer functions,
said weighted sum having a weighing function with range between zero and one, with signal energy quotients of said intermediate functions as argument of said weighing function; and
a code portion for generating said noise reduced output signal based on said weighted sum of said first and said second intermediate function at each of said plurality of frequency components.