Patent ID: 8903101

Claim:
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; and a 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.