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FREQUENCY AND VOLUME RAXGE OF REPRODUCED SOUND 179
reproduction from 16-mm film quite as much as for other reproduction uses (such as broadcast reception, etc.).
Practical Considerations Concerning Frequency Range and Volume Range of Reproduced Sound*
It must be recognized at the outset that the very wide frequency range and the very wide volume range to which the unaided human ear is responsive is quite beyond the capabilities not only of the best commercial 16-mm films and equipment, but also beyond the capabilities of the best 35-mm commercial theatrical films and equipments. Wide ranges approximating 40 to 15,000 cps in frequency and 60 db in volume range have been demonstrated experimentally with the best possible film-recording techniques; public demonstration of such recording was made in 1940 by the Bell Telephone Laboratories with 35-mm film running at 90 ft, per min. The demonstration equipment incorporated almost every known arrangement for maintaining the widest frequency range and volume range — with minimum noise — with little regard (according to 16-mm standards) to cost and complexity of the equipment involved. The result was outstanding, but the cost of a single demonstration unit was about half a million dollars, putting it far beyond commercial reach for 35-mm as well as 16-mm sound film purposes.
Actual Performance — Past, Present, and Future
For the immediate future, it is hardly reasonable to expect 16-mm performance of the best 5% of projectors and films to go beyond range F (110 to 5300 cps) under average noise conditions. Median performance in the near future will probably be in range G (130 to 4400 cps) and poor performance in range H (160 to 3600 cps). These estimates assume new projectors with new films under improved conditions of machine and film manufacture and use.
At the present time, 16-mm sound film performance occurs almost entirely in the low-fidelity range. The median performance is probably in range H (160 to 3600 cps) ; the performance of the poorest 5% may be as low as range J (220 to 2700 cps) . On the whole 16-mm performance has not been good ; during World War II, for example, some prints de
*The general conclusions drawn in this chapter are based upon conventional single-channel (monaural) reproducing systems and do not anticipate stereophonic or other binaural systems.