Granted Patent
Utility
US 5,673,325 · App. 08/339,126
Noise cancellation apparatus
Inventors:
Douglas Andrea, Martin Topf
Patented Case
View Patent ↗
Granted: Sep 30, 1997
Filed: Nov 14, 1994
Inventors
Douglas Andrea
Martin Topf
Assignee (at issue)
Andrea Electronics Corporation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.