New C.B.S. Program Transmission Standards

Over a period of years, broadcast listeners have complained that the musical portions of radio programs are sometimes unpleasantly loud-that is, music is too loud compared with speech. Two surveys conducted by the Columbia Broadcasting System in 1940 and 1944 found this to be true of all broadcast stations, and established the validity of the complaints. This led to more definitive studies. Two related listener studies in 1945 were undertaken, to (1) discover proper (pleasing-to-listener) relative levels at which music and speech should be transmitted, and (2) determine the range within which the peak levels of a program should fall in order to please the largest number of listeners. A total of 224 persons, representing a cross section of the radio audience, took part in individual listener tests. In both studies the listeners, one at a time, heard a series of passages from radio programs. They were asked to adjust the volume of each passage to the most pleasant listening level. Every variable which could be anticipated was provided for, including such matters as introducing controls to account for differences in room noise levels. The major findings of the studies were as follows: (1) Listeners prefer to hear broadcast music and speech at about the same peak levels (as read on a standard volume indicator). (2) The limit of the range of peak volume levels tolerated by the largest number of listeners is approximately 8 db (4 db above or below the average peak-volume level of the passage.