Patent ID: 11889267
Assignee: AMS AG
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 7:
8. A method for adjusting a target transfer function of a noise cancellation enabled audio system comprising an audio processor and an ear mountable playback device further comprising a speaker and at least one feedforward microphone, the method comprising:
receiving using the feedforward microphone an input signal from a feedforward microphone, the input signal being indicative of ambient noise, and, using the audio processor:
determining a filter transfer function to realize a predetermined target transfer function, wherein the target transfer function is configured to attenuate and/or amplify the input signal in a predetermined frequency range,
adjusting a filter function of at least one filter of the noise cancellation enabled audio system depending on the filter transfer function,
providing acoustic transfer functions between an ambient sound source creating the ambient noise and an eardrum exposed to the speaker, and
determining the filter transfer function by compensating for the acoustic transfer functions, and
wherein the acoustic transfer functions comprise:
a first acoustic transfer function of the feedforward microphone, denoted H_M(s),
a second acoustic transfer function of an amplifier, denoted H_A(s),
a third acoustic transfer function of the speaker, denoted H_S(s),
a fourth acoustic transfer function of the ear mountable playback device, denoted H_H(s); and wherein:
the filter transfer function, denoted H_F(s), is determined as, H
    F
   
   (
   s
   )
  
  =
  
   
    
     
      H
      T
     
     (
     s
     )
    
    -
    
     
      H
      H
     
     (
     s
     )
    
   
   
    
     
      H
      M
     
     (
     s
     )
    
    ·
    
     
      H
      A
     
     (
     s
     )
    
    ·
    
     
      H
      S
     
     (
     s
     )
    
   
  
 

wherein H_T(s) denotes the target transfer function.