Granted Patent
Utility
US 4,319,081 · App. 06/074,767
Sound level monitoring apparatus
Inventors:
Michael C. Martin, Ian Summers
Patented Case
View Patent ↗
Granted: Mar 9, 1982
Filed: Sep 11, 1979
Inventors
Michael C. Martin
Ian Summers
Assignee (at issue)
NATIONAL RESEARCH DEVELOPMENT 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.