Motion Picture Herald (Oct-Dec 1932)

November 10, 1012 Motion Picture Herald 25 is made uncomfortable by excessive loudness, or reverberation, the sound is obviously bad. In the case of music, if the listener is constantly hearing a certain group of tones accentuated more than the rest, the reproduction is not a true one. The theatre itself must be considered in relation to sound : its acoustics are the last link in the chain. The same music may be heard very differently in two theatres with differing acoustic properties. The acoustic factors in sound projection are noise, echo, reverberation and distribution. All are factors to be considered if sound that is good at the horns is to remain good in the auditorium. Noise, whether from inside or outside sources, reduces the intelligibility of reproduced sound in addition to being distracting. Care should be exercised to keep down noise intensity in every way. Its effect on sound is similar to the effect on pictures of excess: one doesn't attempt to project motion pictures in well illuminated surroundings. Echoes are a rarer source of disturbance. With echoes the sound appears not only to be delayed, but to issue from some point behind the auditor while the action accompanying it appears on the stage. They annoy and confuse in the theatre. They usually consist of reflections from hard curved surfaces in the ceiling, or back wall which may be treated with, sound absorbing material. Reverberation is the name given the sound heard in a room after the source which produced it has stopped. It is due to random reflection of sound between the room walls as it gradually decays. It differs from echo in that it appears as a continuation of the original sound rather than a repetition after an interval. Sounds do not disappear instantaneously but have to be absorbed in some manner. Now some reverberation is desirable to impart a "live" quality to music, so that it is troublesome when in excess of a certain known optimum amount. The remedy is to make the auditorium walls more absorbing by applying materials designed for this purpose according to the result of an analysis. The last item is distribution, the business of having sufficient intensity at every seat. There is a range of intensities which are most suitable for audition. Sound must not be too loud for comfort at one point and too weak to be intelligible at some other. The matter should not be left to chance when everything else has been scientifically designed. Proper arrangement of the sound sources is essential. Directional sources are a great help. Balcony and orchestra slopes may be designed so as to simplify the problem. Broadly speaking, the acoustic quality of a theatre is determined by the naturalness with which sound is conveyed from the sound source to the listeners. It must not be jumbled by excessive reverberation or by echoes; it must not be masked by the noise of ventilators and projection room machinery ; and it must not be too loud or too soft for comfortable hearing. These factors need constitute atention. SUN-ARC CARBONS FOR PERFECT PROJECTION "Best by Test" BIG SAVING — COMPLETE SATISFACTION BETTER LIGHT — SLOWER BURNING CARBON SAVERS (Patent pending) free of charge. 2 Savers for each Theatre. Burn Hilow and High Intensity down to 2 inches and less. CARBONS FURNISHED READY FOR USE WITH THE SAVER. No inconvenience whatsoever for the operator. HIGH INTENSITY CARBONS 13.6 are furnished 22 inches long. Hi-Low Carbons (for 60-85 amps.) are precratered. SAMPLES ON REQUEST CARBON PRODUCTS, INC 324 WEST 42nd STREET NEW YORK CITY PROJECTIONIST SPEAKS " — and after installing same, without even testing, we ran a full show without the slightest trouble. We have had no trouble since then whatever with the equipment. "Very simple to operate, with direct drive, and with only one extra sprocket to thread, we find it to be very, very good; producing a smooth, clear and undistorted reproduction of recordings." C T. Sims, Projectionist, Rex Theatre; Bay Mmette, Ala. Complete Equipment for Holmes, Simplex, Powers, Kaplan, Superior 9 LEROY MASTER MODEL FEATURES 10O Positions for wear adjustment front edge film guide. Film Sprocket guide roller locks out of way — easy threading. Precision Lens and .highly corrected slit. Projects, maximum amount of light. Will reproduce, clearly, 8.000 cycles plus. WRITE OR WIRE 421 LYELL AVENUE ROCHESTER, N. Y. URox So**%a**»WT Corp. Preliminary Acoustic Analysis Send me a plan or sketch of your auditorium and without cost to you I will examine same and advise you whether your house can be economically corrected. S. S. SUGAR Acoustician 8 W. 40th St., New York, N. Y.