Patent ID: 6327368
Filing Date: 2001-12-04
Classification: G10K

Abstract:
A configuration of providing a microphone in a duct having an air current therein, for use in an active noise reduction device having said microphone pick up noise propagating in said duct, having a speaker producing sounds counteracting said noise, and having an auxiliary microphone provided downstream from said microphone for picking up remnant noise, said speaker and said auxiliary microphone forming a closed loop for suppressing said remnant noise, said configuration comprising:an expanded room formed by enlarging an area of a cross section of part of said duct, said cross section being perpendicular to a direction of the air current, the air current having a decrease in velocity when coming into said expanded room,wherein said microphone, provided upstream from said auxiliary microphone and farther from said speaker than said auxiliary microphone, is contained in said expanded room for picking up said noise, the decrease in velocity of the air current reducing an effect of the air current on said microphone in picking up said noise.