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Time after time I have heard this item portrayed by a sudden welter of earth-shattering sound and ear-splitting screams. This is way off the mark. The earthquake effect is done in four separate parts, with a few seconds pause between each. Start with a low, shuddering rumble, bring up the gain slowly, hold for a second or two, then drop it back almost to zero. Make the sound itself by shaking two rubber balls around in a cardboard box and recording the sound at double-speed or, if you are able to do so, recording at 15 ips and playing back at 3¾ ips. Having recorded the first part of the “quake” (or “prelude” as it is known), follow on with one or two isolated crockery-smashes and mix-in once more to the rumbling effect, louder this time. Now bring in a sudden sliding, crashing sound, with a tearing metallic “ring” about it. This can be achieved by dropping a quantity of small stones on to the sloping lid of a cardboard box. The lid should be held about a foot above the table surface with a glass jam-jar (lying on its side) at the lower end of the slope. The sound sequence, thus, is that the stones strike the lid of the box, slide down its surface and strike against the side of the jam-jar before coming to rest on the table top. Record the sound at absolute maximum gain. Double-speeding may improve the item still further by both lengthening the sound and giving it a “heavier” quality. Lastly, fade in the rumbling noises once more, hold, then fade to zero. Incidentally, a most uncanny yet effective impression of brooding silence can be obtained between the individual portions of activity by recording very faintly, the sound of distant voices alone. “Panic” noises such as screaming and shouting, if desired, are best recorded ehind the third “falling-debris” section which may be superimposed over it.
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R. Murray Schafer (The Soundscape: Our Sonic Environment and the Tuning of the World)