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Projection engineering (Sept 1929-Nov 1930)

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Page 6 Projection Engineering, June, 1930 Your positive assurance of splendid hearing conditions WHEN you properly correct the acoustics of your theatre with Acousti Celotex, you are definitely assured of excellent hearing conditions for sound pictures. For Acousti-Celotex is installed according to the detailed recommendations of our skilled acoustical engineers. The accuracy of these recommendations has been checked and proved in hundreds of installations. The Fischer Theatre, Danville, Illinois, is a typical case. Acoustical analysis considered the upholstered seats, aisle carpets and velour drapes. It revealed that additional sound absorption was needed to reduce reverberation to the proper period. About 4,300 square feet of type BB Acousti-Celotex with a sound-absorbing coefficient of .70 were applied in the panel of the main ceiling, the center panel of the balcony ceiling and the ceiling of the mezzanine space. To measure results an experienced crew made thorough articulation tests (see Note) Under ideal conditions the tests registered an average accuracy of 93%.' The observers were scattered uniformly about the Fischer Theatre. They showed an average of 91% articulation for two different human voices. Using a specially prepared film with the regular sound equipment, they gave an average of 90% (including even the extreme front portions of the theatre). Since 75% or over is usually considered satisfactory, the hearing conditions are now considered nearly perfect. Submit your acoustical problems to the acoustical engineers of The Celotex Company for study and recommendation — without charge or further obligation. The word Cee-oteX (Heg. U. S. Pat. Off.) is the trademark of and indicates manufacture by The Celotex Company. Chicago, Illinois THE CELOTEX COMPANY 919 N. Michigan Ave., Chicago, Illinois In Canada: Alexander Murray & Co., Ltd., Montreal Sales distributors throughout the World Acoustic-Celotex is sold and installed by approved Acoustic-Celotex contractors. Acousti-Telotex FOR LESS NOISE-BETTER HEARING *Type BB Acousti-Celotex has a soundabsorbing efficiency of 70%. NOTE: In articulation tests a list of meaningless one-syllable words containing common vowels and consonants is called out. Observers record the words they think they hear. Their lists are compared with the original list, and the percentage of accuracy is the articulation percentage of the room. Preliminary readings in a small, quiet, non-reverberant room determine the observers' power of accuracy.