. The Bell System technical journal . elligibility maybe hoped for, although this factor is of little importance, as the presentsystem is satisfactory in this respect. The other improvement mentioned, namely, the volume range, isprobably the more difficult, but is necessary before music can be re- 8 The Nature of Speech and Its Interpretation. Harvey Fletcher, Journal of theFranklin Institute, Vol. 193, No. 6, June, 1922. 122 BELL SYSTEM TECHNICAL JOURNAL produced in a perfect manner. Rough experimental data indicatethat the loudness in an orchestra selection may vary from one partof the selec
. The Bell System technical journal . elligibility maybe hoped for, although this factor is of little importance, as the presentsystem is satisfactory in this respect. The other improvement mentioned, namely, the volume range, isprobably the more difficult, but is necessary before music can be re- 8 The Nature of Speech and Its Interpretation. Harvey Fletcher, Journal of theFranklin Institute, Vol. 193, No. 6, June, 1922. 122 BELL SYSTEM TECHNICAL JOURNAL produced in a perfect manner. Rough experimental data indicatethat the loudness in an orchestra selection may vary from one partof the selection to another by a ratio as great as 50,000 to 1. Whilethe present equipment does not operate with entire satisfaction overthis range of loudness, it has been found relatively easy to obtaingood results by manual adjustment of the amplification during therendering of the selection. If the gain is varied in small enoughsteps, the change is not noticeable to the listeners. An increase in the loudness range would render the manual ad-. ¥^X-Z Fig- 4. justment unnecessary and would make the reproduction a faithfulduplicate of the music as actually played. Technical Description of the System The foregoing discussion having described the requirements whichmust be met in order that the public address system shall successfullytransmit speech and music, the system in its commercial form will PUBLIC ADDRESS SYSTEMS 123 now be described. In order to make clear the arrangement of theequipment, a typical installation is shown in Fig. 4, this being aninstallation where the audience and speaker are in the open air, andwhere no connection is made with the long distance lines. It mightbe well to state here that with the equipment shown an audience of700,000 can be adequately covered. Some of the sound leaving the speakers mouth is picked up by thetransmitter, on a reading-desk type of pedestal, which is normallymounted at the front of the platform. The feeble currents from the transmitter are
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
