An Electronic Tone Ringer for the Telephone

To meet with the increasing demand for a replacement of the electromechanical ringer in telephone sets, a tone ringer has been developed to fulfill the requirements of pleasantness and detectability in a noisy environment. Paired comparison tests and word profile tests have been carried out on a number of tones. To generate the most preferable tone appearing economically feasible, circuits have been developed that are operated by the normal ringing current. A small size dynamic loudspeaker with ample efficiency and width of frequency range has been chosen as the transducer and properly mounted in a Contempra telephone set. Tests of total subjective loudness gave better results than those of electromechanical ringers. Investigations are continuing to determine user acceptance.