Directional audio signal processing using an oversampled filterbank

Abstract

A directional signal processing system for beamforming information signals. The system includes an oversampled filterbank, which has an analysis filterbank for transforming the information signals in time domain into channel signals in transform domain, a synthesis filterbank and a signal processor. The signal processor processes the outputs of the analysis filterbank for beamforming the information signals. The synthesis filterbank transforms the outputs of the signal processor to a single information signal in time domain.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to copending Canadian Patent Application entitled, “Directional Audio Signal Processing Using an Oversampled Filterbank,” having serial number 2,354,858, filed Aug. 8, 2001, which is entirely incorporated herein by reference. This application is a Continuation-In-Part application of U.S. patent application Ser. No., 10 / 214,350 filed on Aug. 7, 2002, which has been allowed and which is incorporated by reference herein in its entirety.FIELD OF THE INVENTION [0002] The present invention relates to audio signal processing applications where the direction of arrival of the audio signal(s) is the primary parameter for signal processing. The invention can be used in any application that requires the input audio signal(s) to be processed based on the spatial direction from which the signal arrives. [0003] Application of this invention includes, but is not limited to audio surveillance systems, hearing aids, voic...

AI Technical Summary

Benefits of technology

[0015] The sub-band signal processing approach described henceforth, with its corresponding FFT-based method being one possible embodiment of the oversampled filterbanks employed in the invention disclosed herein, has the advantage of directly addressing the frequency-dependent characteristics in the directional processing of broadband signals. Compared to traditional time-domain and FFT-based approaches, the advantages of using an oversampled filterbank in sub-band signal processing according to the present invention are as follows: 1) Equal or greater signal processing capability at a fraction of the processing power, 2) Orthogonalization effect of the subband signals in the different frequency bins due to the FFT of the oversampled filterbank, 3) Improved high frequency resolution, 4) Better spatial filtering, 5) Wide range of gain adjustment at a very low cost of processing power, and 6) Ease of integration with other algorithms.

Problems solved by technology

To deal with complex broadband signals such as speech however, these time-domain approaches generally provide poor performance unless significant extra resources, such as large microphone arrays, lengthy filters complex post-filtering, and high processing power are committed to the application.

However, many of these EFT-based approaches suffer from wide sub-bands that are highly overlapped, and therefore provide poor 5 frequency resolution.

They also require longer group delays and more process in, power in computing the EFT.

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