Adaptive filter for correcting the transfer characteristic of electroacoustic transducer

An arrangement for converting an electric input signal into an acoustic or a mechanic output signal using a transducer and additional means for compensating for distortions of said transducer adaptively in normal working mode to realize a desired overall transfer characteristic of the said arrangement without pre-training, wherein said means comprises:

• a correction filter with controllable linear or nonlinear transfer characteristic having a filter input supplied with said input signal and filter output connected to the electric input of said transducer for realizing said desired overall transfer characteristic between said input signal and said output signal, said correction filter also having for every controllable filter parameter a control input for changing said filter parameter and a gradient output for providing a gradient signal;
• wherein said correction filter comprises
• an input circuit having an input connected to said filter input;
• also having for every said filter parameter an output connected to corresponding said gradient output for providing a gradient signal;
• a controllable amplifier for every said filter parameter having a signal input also connected to the output of said input circuit, a gain control input connected to said control input and an amplifier output for providing a scaled gradient signal;
• and
• a output circuit having an input for every said filter parameter and an output connected to said filter output;
• every said amplifier output being connected to corresponding input of said output circuit;
• a sensing circuit having an error output for providing an error signal, said error signal describing the deviation of the instantaneous overall transfer characteristic of said filter connected with said transducer from said desired overall transfer characteristic;
• and
• a controller having an error input connected to said error output, said controller also having for every said filter parameter a gradient input and control output, every said gradient input being connected to corresponding said gradient output and every said controller output being connected to corresponding said control input for generating a control signal to adjust adaptively corresponding said filter parameter and for reducing the amplitude of said error signal.