Sound Recording for Films - The History and Development of Sound Recording

By Arthur Pereira

Many of the earliest books, particularly those dating back to the 1900s and before, are now extremely scarce and increasingly expensive. We are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.

• Language: English
• Publisher: Read Books Ltd.
• Release date: Sep 15, 2016
• ISBN: 9781473358379

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SOUND ON DISC

For these reasons—its lesser cost and relative ease in working—‘sound on disc’ is pre-eminently in favour among amateurs as a recording medium just as, prior to 1927, it was the one resource of the professional cinema. As early as 1912 Leon Gaumont in France and T. C. Hepworth in England were exploiting the idea with the somewhat primitive means then at their disposal. Even in quite recent times some remarkable records of opera and musical plays have been produced in this way.

Fig. 112

Sound Waves

The study of acoustics, or the phenomena of sound has, in recent years made tremendous strides, particularly in the domain of its registering and reproduction. Nevertheless, the vibratory nature of sound has long been common knowledge, the name of the French physicist Marey being, among others, associated therewith. By the graphic recording of sounds, as well as by their analysis with vibrating flames, Marey showed that a thin membrane stretched between its extremities could be made to vibrate by the influence of sound waves, no matter what their source. He compared them with the concentric waves set up on the surface of water about a point which was regularly agitated by some shock or collision, and pointed out that the movement of the membrane was analogous to that of a cork floating on the water (Fig. 113). These waves are characterised by a series of oscillations of which the number per second is known as the frequency or pitch of the sound, while the amplitude of the vibration represents the sound’s intensity.

Fig. 113

The human ear is very sensitive to quite small variations of frequencies. Fig. 114 shows their distribution on the keyboard of a standard piano and also the registers of the commoner musical instruments and the human voice.

Pure sounds are rare, the tuning fork and oscillating valve perhaps alone in emitting them. Others include reverberations and interferences, added to their respective harmonics of higher frequencies. These last are characterised by their order, 2, 3, 4, 5, etc., that is to say by the factor of multiplication of the fundamental frequency. Harmonics contribute to the formation of that special quality called ‘timbre’ which, for example, gives individual character to our speech.

Whilst fundamental sounds rarely pass beyond a frequency of 5,000 cycles per second, harmonics may extend to 15,000 cycles. Certain noises such as the rubbing of paper or hissing may correspond to oscillations as high even as 10,000—12,000 cycles per second.

The limit of hearing in a young person may extend as high as 20,000 cycles per second, but in the generality of cases the upper limit is much lower than that, and falls with age from about 15,000 to 10,000. At the other end of the scale sound sensation commences at about 16 cycles per second and becomes musical at about 40 cycles.

Fig. 114