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:
Jan. 25, 2005
Filed:
Sep. 09, 1998
Seppo Uosukainen, Helsinki, FI;
Vesa Välimäki, Espoo, FI;
Kari Kirjavainen, Espoo, FI;
Jukka Lekkala, Tampere, FI;
Hannu Nykänen, Tampere, FI;
Seppo Uosukainen, Helsinki, FI;
Vesa Välimäki, Espoo, FI;
Kari Kirjavainen, Espoo, FI;
Jukka Lekkala, Tampere, FI;
Hannu Nykänen, Tampere, FI;
VTT, Espoo, FI;
Abstract
The invention relates to a method and an equipment for attenuating sound in a duct. Sound propagating in a duct is detected by means of a detector () and attenuated by using two successive monopole elements () in such a way that both elements function as a dipole approximation and the elements are also used to approximatively produce the monopole radiation needed. A dipole control signal is fed to both elements () at a phase shift which is 180° between the two elements. In addition, a monopole control signal is fed to the same elements (), only this time cophasally. Total volume velocities produced by the two elements () are combinations of the portions obtained from the monopole and dipole sources.