Patent ID: 9264804
Filing Date: 2016-02-16
CPC Classification: H04R

Claim Text:
1. A method in a communication device for suppressing noise of a first signal, captured via a primary microphone, arranged on the communication device such that it is capable of capturing noise and intermittent speech, the noise suppression being executed by processing signal power spectrum estimates of the first signal and a second signal, captured via a reference microphone arranged on the communication device, such that it is capable of capturing noise at substantially the same signal level as the primary microphone and speech at a lower signal level than the primary microphone, the method comprising: determining, on the basis of characteristics of the signal power spectrum estimate of the first signal, whether the first signal comprises non-stationary signal components or substantially stationary noise; responsive to determining that the first signal comprises substantially non-stationary signal components, determining, on the basis of an inter-microphone gain offset and a ratio of the first signal and the second signal, whether the first signal comprises near-field signal components or substantially far-field noise; responsive to determining that the first signal comprises substantially stationary noise, updating a noise power spectrum estimate of the first signal with a stationary noise power spectrum estimate; responsive to determining that the first signal comprises substantially far-field noise, updating the noise power spectrum estimate of the first signal with a far-field noise power spectrum estimate; computing a frequency response of a noise suppressing filter on the basis of the noise power spectrum estimate, suppressing noise from the first signal by applying the noise suppressing filter with said frequency response on said first signal; and calculating a signal power spectrum ratio as a ratio of a first power spectrum estimated for the first signal and a second power spectrum estimated for the second signal, and either responsive to the power spectrum ratio being calculated when the first signal was determined to comprise substantially stationary noise, updating the inter-microphone gain offset on the basis of the signal power spectrum ratio, or responsive to the power spectrum ratio being calculated when the first signal was determined to comprise non-stationary signal components, determining whether the first signal comprises substantially far-field noise by comparing the signal power spectrum ratio to the most recently updated inter-microphone gain offset.