1. The branch of science devoted to the
transmission, reception, and reproduction of sounds, such as speech and tones that represent digits for
signaling.
Note 1: Transmission may be via various media, such as wire, optical fibers, or
radio.
Note 2: Analog representations of sounds may be digitized, transmitted, and, on reception, converted back to analog form.
Note 3: "Telephony" originally entailed only the transmission of voice and
voice-frequency data. Currently, it includes new services, such as the transmission of
graphics information.
2. A form of
telecommunication set up for the transmission of speech or, in some cases, other sounds. [
NTIA] [
RR]