Electrical audio signal processing systems and devices – Acoustical noise or sound cancellation – Adjacent ear
Patent
1990-01-22
1991-04-23
Ng, Jin F.
Electrical audio signal processing systems and devices
Acoustical noise or sound cancellation
Adjacent ear
G10K 1116
Patent
active
050105760
ABSTRACT:
An active acoustic attenuation system for attenuating tonal blade pass noise in a multi-bladed fan uses a sinusoidal rotational speed signal produced by an accelerometer mounted on the fan as the reference signal for a filtered-X LMS (least mean squarae) adaptive filter controlling a canceling sound generating speaker. The sinusoidal signal is clipped by a zero crossing detector to produce a rectangular wave signal having harmonics which include the fundamental and harmonics of the tonal noise to be eliminated. When the system is used with axial flow fans having a central hub, the speaker is mounted facing the fan and coaxial with the hub. When the fan has a straight discharge conduit, the speaker is no larger in diameter than the fan hub to preclude restricting flow; however, there is no restriction on the size of a speaker facing the fan when it is mounted in the rear wall of a discharge chamber having a lateral discharge opening.
REFERENCES:
patent: 3502911 (1970-03-01), Lehman
patent: 4473906 (1984-09-01), Warnaka et al.
patent: 4506380 (1985-03-01), Matsui
patent: 4677677 (1987-06-01), Eriksson
Samuel D. Stearns, Adaptive Signal Processing, Prentice Hall, Inc., 1985, pp. 288-292.
G. H. Koopmann et al., Active Source Cancellation of the Blade Tone Fundamental and Harmonics in Centrifugal Fans, Journal of Sound and Vibration, Academic Press Limited, 1988, pp. 209-220.
IBM Technical Disclosure Buleltin, "Audible Noise Suppression," vol. 31, No. 8, Jan. 1989, pp. 256-258.
Chen Sylvia
Ng Jin F.
Telfer G. H.
Westinghouse Electric Corp.
LandOfFree
Active acoustic attenuation system for reducing tonal noise in r does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Active acoustic attenuation system for reducing tonal noise in r, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Active acoustic attenuation system for reducing tonal noise in r will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1626625