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.

1 . A directional signal processing system for beamforming a plurality of information signals, said directional signal processing system comprising: 
 a plurality of microphones;    an analog-to-digital convertor for converting a plurality of said information signals from said microphones to a plurality of digital information signals;    an oversampled filterbank comprising at least one analysis filterbank for transforming said digital information signals in time domain into a plurality of channel signals in transform domain, and one synthesis filterbank, said oversampled filterbank being a weighted-overlap-add (WOLA) filterbank, said channel signal being a complex-valued, demodulated time-frequency signal;    a signal processor for processing the outputs of said analysis filterbank for beamforming said information signals, said synthesis filterbank transforming the outputs of said signal processor to a single digital information signal in time domain, said signal processor including at least one of any of the followings:    a) a fixed beamformer receiving the outputs of said analysis filterbank for beamforming said information signals with a specific beampattern,    b) a first multiplier for multiplying the outputs of said fixed beamformer with at least one weight factor,    c) a neural network receiving the outputs of said analysis filterbank, and    d) a second multiplier for multiplying the outputs of said neural network with the outputs of said analysis filterbank, a post filter provided between said signal processor and said synthesis filterbank; a controller for controlling said post filter; and a digital-to-analog convertor for converting said single information signal to analog information signal.    
   
   
       2 . A directional processing system as claimed in  claim 1  further comprising at least one of any one of followings: 
 a voice activity detector operably coupled to at least one of said fixed beamformer and said controller;    a target-to-jammer ratio estimator operably coupled to at least one of said fixed beamformer and said controller;    a signal-to-noise ratio estimator operably coupled to at least one of said fixed beamformer and said controller;    a combination matrix provided between said analog-to-digital convertor and said analysis filterbank for pre-processing of said information signals in time domain;    an active noise processor comprising a microphone and a loop filter.    
   
   
       3 . A directional processing system as claimed in  claim 1 , wherein said transform domain is a frequency domain.  
   
   
       4 . A directional processing system as claimed in  claim 1 , wherein said signal processor further comprises at least one of any of the following: 
 a summation circuit for summing the outputs of said first or second multiplier to form the channel signals;    an adaptive processor for adjusting said weight factor.    
   
   
       5 . A directional processing system as claimed in  claim 2 , wherein said signal processor further comprises at least one of any of the following: 
 a summation circuit for summing the outputs of said first or second multiplier to form the channel signals;    an adaptive processor for adjusting said weight factor.    
   
   
       6 . A directional processing system as claimed in  claim 3 , wherein said signal processor further comprises at least one of any of the following: 
 a summation circuit for summing the outputs of said first or second multiplier to form the channel signals;    an adaptive processor for adjusting said weight factor.    
   
   
       7 . A directional processing system as claimed in  claim 1 , wherein said at least one fixed beamformer comprises: 
 a circuit for processing the channel signals for achieving approximately linear phase response within the channel, the circuit applying one or more filter to at least one channel signal.    
   
   
       8 . A directional processing system as claimed in  claim 2 , wherein said at least one fixed beamformer comprises: 
 a circuit for processing the channel signals for achieving approximately linear phase response within the channel, the circuit applying one or more filter to at least one channel signal.    
   
   
       9 . A directional processing system as claimed in  claim 3 , wherein said at least one fixed beamformer comprises: 
 a circuit for processing the channel signals for achieving approximately linear phase response within the channel, the circuit applying one or more filter to at least one channel signal.    
   
   
       10 . A directional processing system as claimed in  claim 7 , wherein the filter is an IIR filter.  
   
   
       11 . A directional processing system as claimed in  claim 8 , wherein the filter is an IIR filter.  
   
   
       12 . A directional processing system as claimed in  claim 9 , wherein the filter is an IIR filter.  
   
   
       13 . A directional processing system as claimed in  claim 1 , wherein said neural network is a Cascaded Hybrid Neural Network.  
   
   
       14 . A directional processing system as claimed in  claim 2 , wherein said neural network is a Cascaded Hybrid Neural Network.  
   
   
       15 . A directional processing system as claimed in  claim 3 , wherein said neural network is a Cascaded Hybrid Neural Network.