Patent ID: 7885415

Claim:
A device for reducing sound of a noise source generating a primary sound wave in narrow frequency ranges by superpositioning sound waves, comprising: an electroacoustic transducer generating a secondary sound wave, the electroacoustic transducer comprising a suspended membrane having a spring stiffness and an adjustment mechanism capable of changing the spring stiffness of the suspended membrane; at least one sound pickup; a control unit; wherein said at least one sound pickup is set up to measure an error signal of the primary sound wave and of the secondary sound wave; wherein said at least one sound pickup is coupled to said control unit to transmit the error signal to said control unit; wherein said control unit is arranged to receive a reference signal of the noise source and is coupled to the adjustment mechanism of said electroacoustic transducer such that the spring stiffness of the suspended membrane is changed on the basis of the reference signal and the error signal.