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Class Information
Number: 181/18
Name: Acoustics > Speaking tubes > Systems
Description: Construction of speaking-tubes with their associated parts; also "speaking-tube exchanges", also, any patents on speaking-tubes not classified elsewhere.
Patents under this class:
| Patent Number |
Title Of Patent |
Date Issued |
| 7525440 |
Person monitoring |
Apr. 28, 2009 |
| 5209226 |
Underwater respiratory device |
May. 11, 1993 |
| 4932495 |
Vocal sound muffling device |
Jun. 12, 1990 |
| 4926961 |
Hinged acoustical voice tube |
May. 22, 1990 |
| 4839871 |
Underwater communication device |
Jun. 13, 1989 |
| 4527658 |
Bubble silencer for an underwater voice communicator |
Jul. 9, 1985 |
| 4527657 |
Tapered tube impedance matching underwater voice communicator with bubble silencer |
Jul. 9, 1985 |
| 4505358 |
Voice communicator |
Mar. 19, 1985 |
| 4473130 |
Crash helmet with communication system |
Sep. 25, 1984 |
| 4472607 |
Inflight headset for civil aircraft |
Sep. 18, 1984 |
| 4183422 |
Underwater communications device |
Jan. 15, 1980 |
| 4174155 |
Sound absorbing article and methods of constructing and utilizing same |
Nov. 13, 1979 |
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