Arrangement for suppressing an interfering component of an input signal

Abstract

In an acoustic echocanceller ( 6 ), an estimate of an echo signal is determined by an adaptive filter ( 10 ) and is subtracted from the input signal by a subtracter ( 14 ). The spectrum estimator ( 12 ) determines the frequency spectrum of the estimate of the echo signal, and the filter ( 16 ) filters the output signal of the subtracter ( 14 ) with a filter having a transfer function dependent on the spectrum determined by the estimator ( 12 ). The use of this combination results in a substantial improvement of the suppression of the echo signal.

1. An arrangement for suppressing an interfering component in an input signal, said arrangement comprising: 
 a selection from singular and  plural means for deriving ana summed estimate of the interfering component,;  
 subtraction means for determining a difference signal from the input signal and an interfering estimate selected from  the summed estimate of the interfering component and a sum estimate of at least two interfering components,  ; 
 means for determining an estimate of the frequency spectrum of the summed estimate of the interfering component and an estimate of the frequency spectrum of the sununed interfering components,  ;  
 a filter having an input for receiving said difference signal and an output for an output signal being an estimate of said input signal substantially free of said interfering component, and having a selectable transfer function relating said output to said input of the filter, which transfer function is reduced in value for at least one frequency range for suppressing spectral components of the output signal having a strong contribution from the interfering component,  ; and  
 means for setting the transfer function of the filter in dependence on the estimate of the frequency spectrum of the summed estimate of the interfering component and the estimate of the frequency spectrum of the summed interfering components  to thereby define the at least one frequency range.  
 
     
     
       2. The arrangement according to  claim 1 , wherein the means for determining an estimate of the frequency spectrum of the interfering component is arranged for deriving the estimate of the frequency spectrum of the interfering component from the estimate of the interfering component. 
     
     
       3. The arrangement according to  claim 2 , wherein the filter has a transfer function having an absolute value dependent on the difference of the amplitude of the frequency of the frequency spectrum of the estimate of the interfering component. 
     
     
       4. The arrangement according to  claim 3 ,
 wherein the means for determining an estimate of the frequency spectrum of the interfering component is arranged for determining the frequency of at least one peak in the frequency spectrum, and  
 wherein the filter is arranged for attentuationattenuating spectral components in a frequency range around the frequency of the at least one peak.  
 
     
     
       5. The arrangement according to one of the   claim 2 ,
 wherein the means for determining an estimate of the frequency spectrum of the interfering component is arranged for determining the frequency of at least one peak in the frequency spectrum, and  
 wherein the filter is arranged for attenuating spectral components in a frequency range around the frequency of the at least one peak.  
 
     
     
       6. The arrangement according to  claim 1 , wherein the filter has a transfer function having an absolute value dependent on the difference of the amplitude of the frequency of the frequency spectrum of the estimate of the interfering component. 
     
     
       7. The arrangement according to  claim 6 ,
 wherein the means for determining an estimate of the frequency spectrum of the interfering component is arranged for determining the frequency of at least one peak in the frequency spectrum, and  
 wherein the filter is arranged for attentuatingattenuating spectral components in a frequency range around the frequency of the at least one peak.  
 
     
     
       8. The arrangement according to  claim 1 ,
 wherein the means for determining an estimate of the frequency spectrum of the interfering component is arranged for determining the frequency of at least one peak in the frequency spectrum, and  
 wherein the filter is arranged for attentuatingattenuating spectral components in a frequency range around the frequency of the at least one peak.  
 
     
     
       9. A loudspeaking telephone comprising an arrangement according to  claim 1 . 
     
     
       10. An arrangement for suppressing an interfering component in an input signal, said arrangement comprising:
   a first filter configured to output an estimate of the interfering component;        a subtractor configured to subtract the estimate of the interfering component from the input signal to output a difference signal;        a second filter configured to receive the difference signal and output an output signal, said output signal being an estimate of said input signal substantially free of said interfering component;        wherein said second filter has a selectable transfer function configured to suppress spectral components associated with the interfering component; and        an analyzer configured to receive the estimate of the interfering component and output a control signal for setting the transfer function of the second filter, said control signal being related to a frequency spectrum of the estimate of the interfering component.     
     
     
       11. The arrangement of  claim 10 , further comprising:
   a third filter configured to receive an interfering signal having a second interfering component and to output a further estimate of the second interfering component; and        an adder configured to add the estimate of the interfering component and the further estimate to form an overall estimate of interfering components for input to said second filter and to said analyzer.