Patent ID: 7120261

Claim:
A vehicle accessory, comprising: a housing; at least one first transducer positioned in said housing; at least one second transducer positioned in said housing, wherein the first and second transducers are positioned in spaced relation; and a circuit coupled to the first and second transducers for combining the output signal of the first and second transducers to produce a signal with a reduced noise component, wherein the circuit subtracts the signal from the at least one first transducer from the signal from the at least one second transducer, wherein the at least one first transducer has a front face ported to the front of the housing and the at least one second transducer has a front face ported to the rear of the housing, the at least one first transducer is closer to front ports provided in the housing than the at least one second transducer, the rear of the at least one second transducer is ported to the front of the housing, the at least one first and second transducers are substantially the same, and a distance between the at least one first transducer and front housing ports provided in the housing is substantially equal to a distance between the at least one second transducer and rear housing ports provided in the housing.