(under subclass 150) Subject matter having a single device which converts sound waves to electrical variations and electrical variations to sound waves.
(1) Note. For classification herein, conversion in both directions must be specifically included.
SEE OR SEARCH CLASS
379, Telephonic Communications,
420, for a loudspeaking type telephone set with a single bi-directional transducer; subclass 433 for a handset having a single bi-directional transducer.
