The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 21, 1989
Filed:
Mar. 16, 1988
Applicant:
Inventors:
Larry J Eriksson, Madison, WI (US);
Mark C Allie, Oregon, WI (US);
Richard H Hoops, Stoughton, WI (US);
Assignee:
Nelson Industries, Inc., Stoughton, WI (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04B / ; H04R / ;
U.S. Cl.
CPC ...
381 71 ; 381 94 ;
Abstract
A system is provided for increasing the frequency range of an active acoustic attenuation system in a duct without increasing cut-off frequency f.sub.c of the duct or otherwise splitting or partitioning the duct into separate ducts or chambers. The frequency range is increased above f.sub.c to include higher order modes. A plurality of cancelling model sets are provided. Each transverse portion of the acoustic pressure wave has its own set of an adaptive filter model, cancelling speaker, and error microphone. A single input microphone may service all sets.