Electronic muffler

A muffler for suppressing noise emitted by an engine's exhaust, comprising:

• a housing, including an acoustically tuned front volume and at least first and second rear volumes, wherein said front volume is closed to the exterior of said housing;
• an exhaust duct connected to said engine's exhaust for transporting the engine exhaust, wherein said exhaust duct extends through said front volume and terminates outside of said front volume;
• a cancellation signal generator for receiving residual signals corresponding to the engine noise and generating drive signals according to said received residual signals;
• a plurality of audio transducers, each of said transducers having a front surface and a rear surface, said front surface being acoustically coupled to said front volume, said rear surface being acoustically coupled to a corresponding one of said rear volumes, said audio transducers being adapted to receive said drive signals from said cancellation signal generator and generate anti-noise according to said received drive signals;
• and
• a microphone responsive to the noise emitted by the engine for generating electrical signals corresponding to the detected noise and providing said generated electrical signals to said cancellation signal generator.

A muffler for suppressing noise emitted by an engine's exhaust, comprising:

• a housing, including:
• an acoustically tuned front volume having an outlet;
• a mixing chamber;
• and
• a plurality of acoustic chambers, wherein each of said acoustic chambers is acoustically isolated from other acoustic chambers;
• an exhaust duct connect to said engine's exhaust for transporting the engine exhaust, wherein said exhaust duct extends through said front volume and terminates in said mixing chamber;
• a cancellation signal generator for receiving residual signals corresponding to the engine noise and generating drive signals according to said received residual signals, wherein said cancellation signal generator includes means for separating said received residual signals into components within predetermined frequency ranges;
• a plurality of audio transducers, each of said transducers having a front surface acoustically coupled to one of said acoustic chambers, each of said audio transducers being adapted to receive said drive signals within one of said predetermined frequency ranges from said cancellation signal generator and generate anti-noise according to said received drive signals, and wherein all of said transducers acoustically coupled to the same acoustic chamber receive drive signals within the same frequency range;
• and
• a microphone responsive to the noise emitted by the engine for generating electrical signals corresponding to the detected noise and providing said generated electrical signals to said cancellation signal generator.