Active acoustic attenuation system with power limiting

An active acoustic attenuation method for attenuating an input acoustic wave comprising:

• introducing a canceling acoustic wave from an output transducer to attenuate said input acoustic wave and yield an attenuated output acoustic wave;
• sensing said output acoustic wave with an error transducer and providing an error signal;
• providing a first adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave;
• providing a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer;
• providing a copy of said second model;
• providing an input to said copy from the output of said first model;
• summing the output of said copy with said error signal and supplying the resultant sum to said error input of said first model.

An active acoustic attenuation system for attenuating an input acoustic wave comprising:

• an output transducer introducing a canceling acoustic wave to attenuate said input acoustic wave and yield an attenuated output acoustic wave;
• an error transducer sensing said output acoustic wave and providing an error signal;
• an adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave;
• a shunt path around said output transducer and preventing overdriving of said output transducer by shunting at least part of said correction signal to said shunt path and away from said output transducer.

An active acoustic attenuation system for attenuating an input acoustic wave comprising:

• an output transducer introducing a canceling acoustic wave to attenuate said input acoustic wave and yield an attenuated output acoustic wave;
• an error transducer sensing said output acoustic wave and providing an error signal;
• a first adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave;
• a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer;
• a copy of said second model having an input from the output of said first model;
• a summer summing the output of said copy with said error signal and supplying the resultant sum to said error input of said first model.

An active acoustic attenuation system for attenuating an input acoustic wave comprising:

• an output transducer introducing a canceling acoustic wave to attenuate said input acoustic wave and yield an attenuated output acoustic wave;
• an error transducer sensing said output acoustic wave and providing an error signal;
• a first adaptive filter model having an error input from the error signal and outputting a correction signal to said output transducer to introduce the canceling acoustic wave, said first adaptive filter model comprising;
• a first algorithm filter having a filter input, a filter output, and an error input from said error transducer;
• a second algorithm filter having a filter input from said correction signal, a filter output, and an error input from said error transducer;
• and
• a first summer having a first input from said filter output of said first algorithm filter, a second input from said filter output of said second algorithm filter, and an output outputting a resultant sum as said correction signal;
• a second adaptive filter model modeling said output transducer and the error path between said output transducer and said error transducer;
• a first copy of said second model, said first copy having an input from said filter input of said first algorithm filter, and having an output to said error input of said first algorithm filter;
• a second copy of said second model, said second copy having an input from said correction signal, and having an output to said error input of said second algorithm filter;
• a shunt path around said output transducer and preventing overdriving of said output transducer by shunting at least part of said correction signal to said shunt path and away from said output transducer, said shunt path including said second copy.