Title:
Public-address system
United States Patent 1642040


Inventors:
Mccutchen, Brunson S.
Application Number:
US7511625A
Publication Date:
09/13/1927
Filing Date:
12/12/1925
Assignee:
AMERICAN TELEPHONE & TELEGRAPH
Primary Class:
Other Classes:
84/DIG.26
International Classes:
H04R27/00
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