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J. Perelman
"Entertaining physics". Book 1.
Chapter 10. Sound and hearing


So amaze us “miracles”performed by ventriloquists, based on the same features of the hearing, about which we spoke in the preceding pages.

“If someone walks on the ridge of the roof, " writes Professor Hampson, a voice inside his house gives the impression of a weak whisper. As it is removed to the edge of the building, the whisper is growing weaker. If we sit in any room of the house, we hear nothing we can say about the direction of the sound and the distance of the speaker face. But to change voices, our minds will lead to the conclusion that speaking face away from us. If the same voice will tell us that its owner is moving on the roof, we can easily believe that statement. If, finally, someone started to talk to this person, though on the outside, and receive meaningful answers, then the illusion would be complete.

These are the conditions under which the ventriloquist. When the turn comes to speak to the man on the roof, the ventriloquist weakly mumbles, and when the turn comes to him, he says full, clear voice in order to emphasize the contrast with another voice. The content of his comments, and answers his imaginary interlocutor reinforces the illusion. The only weak point in this deception could be the fact that the imaginary voice of the person on the outside, actually comes from the man on the stage, i.e., has a false direction.

It should be noted that the name of the ventriloquist is inappropriate. The ventriloquist must hide from his listeners the fact that, when it comes to imaginary partner, he actually says it. For this purpose he uses various tricks. Using any kind of gestures he tries to distract the audience's attention from himself. Leaning to one side and holding a hand to their ear, as if listening, he attempts to hide his lips. When he can not hide his face, then tries to do only the most necessary movement of the lips. This helps the fact that often require only a vague, weak whisper. The lips are hidden so well that some people think the performer's voice comes from somewhere in the depths of his body, hence the name: the ventriloquist.

So, imaginary wonders of trewavasae entirely based only on the fact that we are not able precisely to define the direction of the sound, nor the distance of the sounding body. In normal circumstances we do this only approximate; but enough to put us in not the usual conditions of perception of sound - and we already give the most flagrant errors in identifying the source of the sound. Watching a ventriloquist, I could not overcome the illusion, though well understood, what's the matter here.

Entertaining physics J. Perelman


System Orphus


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