Patents by Inventor Donald E. Norgaard

Donald E. Norgaard has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4443889
    Abstract: An improved method and apparatus for reproducing sound includes a third channel which is derived from the pair of signals representing traditional left and right stereophonic channels and which represents a linear algebraic difference between such a pair of signals. A third loudspeaker associated with the third channel povides acoustic radiation as a supplement to acoustic radiation from two laterally-spaced loudspeakers normally used to reproduce respective left and right signal channels. Acoustic radiation from the third loudspeaker is toward a preferred listening region and in a direction substantially opposite to that from the two laterally-spaced left and right loudspeakers which are positioned and oriented to provide essentially codirectional acoustic radiation toward the preferred listening region.
    Type: Grant
    Filed: April 21, 1980
    Date of Patent: April 17, 1984
    Assignee: Nortech Laboratories Ltd.
    Inventor: Donald E. Norgaard