Automatic Control of Aural Program Loudness

The subject of reproduced loudness of aural broadcasting has been one of interest and controversy to broadcast engineers, as well as listeners, for many years. Differences in apparent loudness of various types of program material, all at the same volume indicator level, have been noted on many occasions. The choice of characteristics of the present standard volume indicator, the VU meter, was influenced by the desire to have a closer relation between program level and loudness. There are those who want music as a background and voice announcements, such as news and weather, to be loud enough to be heard under adverse listening conditions, such as in a moving vehicle, and there are those who hold the opposite view as to desirable relative loudness of voice and music. The recent action by the Federal Communications Commission relative to loudness of commercial announcements has stimulated investigations of program loudness, its measurement, and its control in the broadcast system.