US Patent Class 181
ACOUSTICS-- Main Headings
 Electronic File Wrappers |  Electronic Patent Documents |  Paper Patent Documents | Current as of: June, 1999
|  and Services |
| Electronic File Wrappers | Electronic Patent Documents | Paper Patent Documents | Current as of: June, 1999
| and Services |
| CLASS NOTES | ||
| .5 | DF | MISCELLANEOUS |
| * | DF | SPEAKING TUBES {5} |
| 30 | DF | AUDITORIUM |
| 101 | DF | GEOPHYSICAL OR SUBSURFACE EXPLORATION {5} |
| 123 | DF | ECHO SYSTEM {1} |
| 125 | DF | SOUND LOCATION |
| 126 | DF | ANATOMIC OR PROSTHETIC RELATION {2} |
| 138 | DF | MECHANICAL TELEPHONE |
| 139 | DF | WAVE GENERATION AND DETECTION |
| 140 | DF | WITH VESSEL |
| 141 | DF | COMBINED |
| 142 | DF | WAVE GENERATION |
| 143 | DF | MOVING SOUND PRODUCER OR DEFLECTOR |
| 144 | DF | PLURAL DIAPHRAGM SOUND SOURCES {3} |
| 148 | DF | DIAPHRAGM AND ENCLOSURE {8} |
| 157 | DF | DIAPHRAGM {10} |
| 175 | DF | SOUND-MODIFYING MEANS {12} |
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| CROSS-REFERENCE ART COLLECTIONS | ||
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| 400 | DF | WAVE COUPLING {2} |
| 403 | DF | REFRIGERATOR COMPRESSSOR MUFFLER |
| 404 | DF | HOBBY CRAFT ENGINE MUFFLER |