A procedure for transmitting the letters of the alphabet by tone‐coded signals was examined in quiet and against a noise background. The procedure employed successive selections, each from among a small number of alternatives, in order to transmit a target‐vocabulary of 25 letters. Four stimulus variables: tonal frequency, sound level, location, and duration were examined, one at a time. Successive selections were made among two, three, and five alternatives per variable. With less than 1 min of practice at slow rates of presentation with the two‐alternative frequency code, naive listeners were able to receive the entire vocabulary with insignificant error. The highest transmission rate was obtained with a three‐alternative, frequency‐coded display, at only about 1.5 bits per sec. Transmission of tone‐coded signals in noise was nearly equivalent to that in the quiet, when the tonal signals were about 3 db above masked threshold.