An appraisal of received telephone speech volume

One of the attributes of telephone service which is of importance to a telephone user is the loudness with which he hears the voice of a distant talker. Related to this loudness is an objective measurement of “received volume.” This paper represents the results of subjective tests made to determine a relationship between received volume and the satisfaction of telephone listeners. The results are shown as statistical distributions of listeners' opinion, which may be combined with estimated distributions of received volume in the telephone plant to give “grade of service.” Grade of service objectives have been stated as 95 per cent of connections rated “Good”, 5 per cent “Fair” and a negligible percentage “Poor.” Increased use of the more efficient 500-type telephone sets, and planned improvements in the circuits which interconnect them, will make it possible to meet these objectives.