Active noise attenuation system

DETAILED DESCRIPTION In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims.
Referring to FIG.
1, an inlet duct section 10 is shown forming a part of an air induction system of an internal combustion engine 12 connected to a throttle body 14 included in the engine air induction system, both indicated diagrammatically.
The inlet duct section 10 outwardly flares to accommodate a fairing body 16 suspended concentrically within the inlet duct section 10 with integral struts 18, 19 arranged about an annular passage 20 defined between the exterior of the fairing body and the interior of the duct section 10.
A flared bell mouth 22 extends from the open end of the air duct section 10.
An annular air filter element 36 is pressed into the annular passage 20.
The fairing body 16 is hollow and generally cylindrical in shape, but with a tapered end 24 disposed downstream within the air inlet duct 10.
A forward parabolic fairing piece 26 of open cell foam is attached at the front upstream end 28 of the fairing body 16, while an aft parabolic fairing piece 30, also of open cell foam, is attached to the downstream end of the fairing body 16.
Thus, air flow can be drawn into the duct 10 with only a minimal restriction resulting from the presence of the fairing body 16.
A loudspeaker 32 is mounted within the chamber 34 inside the hollow fairing body 16, the loudspeaker 32 facing outwardly and having its cone front located in the plane A (FIG.
3) of inlet opening defined where the annular passage 20 meets the beginning of the bell mouth 22.
The fairing piece 26, being of open cell foam, is acoustically transparent to the sound field broadcast by the loudspeaker 32