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![[Search a list of Patent Appplications for class 381]](../as.gif) Class 381 | ELECTRICAL AUDIO SIGNAL PROCESSING SYSTEMS AND DEVICES |
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![[List of Patents for class 381 subclass 1]](../ps.gif) | 1 | BINAURAL AND STEREOPHONIC |
| | 2 |  Broadcast or multiplex stereo |
| | 17 | Pseudo stereophonic |
| | 19 | Quadrasonic |
| | 23.1 | Hearing aid |
| | 300 | Stereo speaker arrangement |
| | 301 |  In furniture or clothing |
| | 302 | In vehicle |
| | 303 | Optimization |
| | 306 | With image presentation means |
| | 307 | Surround (i.e., front plus rear or side) |
| | 308 | In single baffle |
| | 309 | Stereo earphone |
| | 26 | Stereo sound pickup device (microphone) |
| | 27 | Center channel |
| | 28 | Amplifier |
| | 54 | HELIUM SPEECH |
| | 55 | AUDIO TRANSDUCER PROTECTION CIRCUITRY |
| | 56 | MONITORING OF SOUND |
| | 58 | MONITORING/MEASURING OF AUDIO DEVICES |
| | 61 | SOUND EFFECTS |
| | 66 | DEREVERBERATORS |
| | 67 | STETHOSCOPES, ELECTRICAL |
| | 312 | HEARING AIDS, ELECTRICAL |
| | 313 | Directional |
| | 314 | Programming interface circuitry |
| | 315 | Remote control, wireless, or alarm |
| | 316 | Frequency transposition |
| | 317 | Noise compensation circuit |
| | 319 | With vacuum tube amplifier |
| | 320 | Spectral control |
| | 321 | Wideband gain control |
| | 322 | Specified casing or housing |
| | 70 | ARTIFICIAL LARYNX, ELECTRICAL |
| | 71.1 | ACOUSTICAL NOISE OR SOUND CANCELLATION |
| | 71.2 | Acoustic, nonairborne vibration sensing or counterwave emission |
| | 71.3 | From appliance |
| | 71.4 | Within cabin or compartment of vehicle |
| | 71.5 | Within duct |
| | 71.6 | Adjacent ear |
| | 71.7 | Particular transducer or enclosure structure |
| | 71.8 | Counterwave generation control path |
| | 72 | HEARING PROTECTORS, ELECTRICAL |
| | 73.1 | SOUND OR NOISE MASKING |
| | 74 | HEADPHONE CIRCUITS |
| | 75 | MEGAPHONES |
| | 76 | LECTERNS |
| | 77 | ONE-WAY AUDIO SIGNAL PROGRAM DISTRIBUTION |
| | 86 | VEHICLE |
| | 87 | HAVING NON-ELECTRICAL FEATURE (E.G., MOUNTING) |
| | 89 | Loudspeakers driven in given phase relationship |
| | 332 | And loudspeaker |
| | 333 | With furniture, clothing, or image presentation means |
| | 334 | Portable or for use in diverse environment |
| | 335 | Plural diaphragms, compartments, or housings |
| | 336 | Curved or angled housing |
| | 91 | Having microphone |
| | 92 | DIRECTIVE CIRCUITS FOR MICROPHONES |
| | 93 | FEEDBACK SUPPRESSION |
| | 94.1 | NOISE OR DISTORTION SUPPRESSION |
