Active noise reduction system

摘要

A system for actively reducing noise at a listening point, includes an earphone housing, a transmitting transducer, a receiving transducer and a controller. The transmitting transducer converts a first electric signal into a first acoustic signal, and radiates the first acoustic signal along a first acoustic path having a first transfer characteristic and along a second acoustic path having a second transfer characteristic. The receiving transducer converts the first acoustic signal and ambient noise into a second electrical signal. The controller compensates for the ambient noise by providing a noise reducing electrical signal to the transmitting transducer. The noise reducing electrical signal is derived from a filtered electrical signal that is provided by filtering the second electrical signal with a third transfer characteristic. The second and the third transfer characteristics together model the first transfer characteristic.

主权项

1. An active noise reduction system, comprising:
an earphone to be acoustically coupled to an ear of a user, the earphone comprising
a cupped housing having an aperture;a transmitting transducer that converts a first electrical signal into a first acoustical signal, and that radiates the first acoustical signal to the ear, where the transmitting transducer is arranged at the aperture of the cupped housing thereby defining an earphone cavity; anda receiving transducer that converts a second acoustical signal into a second electrical signal, where the receiving transducer is arranged within the earphone cavity; a first acoustical path that extends from the transmitting transducer to the ear, and that has a first transfer function characteristic indicative of acoustics of the first acoustical path; a second acoustical path that extends from the transmitting transducer to the receiving transducer, and that has a second transfer function characteristic indicative of acoustics of the second acoustical path; and a control unit electrically connected to the receiving transducer and the transmitting transducer, and that compensates for ambient noise by generating a noise reducing electrical signal that is supplied to the transmitting transducer; where the noise reducing electrical signal is derived from a filtered electrical signal, which is provided by filtering the second electrical signal with a third transfer function characteristic; and where the second and the third transfer function characteristics together model the first transfer function characteristic, where the filtered electrical signal is indicative of audio at a virtual receiving transducer position located acoustically downstream of the transmitting transducer.