Was ist eine akustische Täuschung?

What is an auditory illusion?

Maybe you know that you can't always rely on your sensory perception 100%. Surely you know the typical phenomenon of optical illusion. You are probably also familiar with mirages. Here the illusion of proportions or spaces is created. There are also intentional representations, which are used, for example, very much in art, on postcards or in calendars.

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Much less known, however, is that there are also acoustic illusions. The sounds that you perceive from your environment, you sometimes interpret quite differently than they are in reality. In our guide you will learn some examples of this.

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Concealed tones

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It happens that you can hear two tones at the same time that differ very little in terms of pitch. Then you perceive only the louder stimulus consciously. Crucial for this is that one of these two tones is much louder than the other.

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The clever inventors of the MP3 format took advantage of this acoustic illusion. When music is played, some of the sounds can simply be omitted. Some sounds are hardly perceived by humans anyway. This plays an important role in digitization. Data transmission is also affected in the process. The smaller the files, the better. Then, namely, only a minimum space requirement is also necessary to store music files or to transfer them faster on the Internet.

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The Shepard Scale

acoustic phenomenon.

The so-called Shepard scaledeals with an acoustic phenomenon in which several targets are played simultaneously. The sounds are different in the process. Because the volume changes however temporally shifted, you have as a listener the feeling, you would hear a scale. In reality, however, you only hear the same tones, and each of these tones has a different volume. You can find many beautiful sound examples on the Internet. Some of the effects you can perceive are very futuristic. Artists also imitate this illusion, for example in piano pieces. This phenomenon is sometimes even used by organ pipes in certain melodies. This creates a very floating sound experience.

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Melodies with mysterious background

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Diana Deutsch is a well-known American music psychologist. She has found in her studies that it is mostly impossible to recognize randomly chosen fragments from a melody without a coherent context. However, once the subject has heard the complete piece of music, it is possible for him to deduce the entire melody from the fragments. Your brain can fill in the missing passages as needed. In the head, you then hear the whole song, although you can perceive only individual tones of it.

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Spatial sound effect through stereophony

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A special spatial sound effect can be created with the help of stereophony. Basically, only two different speaker systems are needed for this, which reproduce the sounds. With a clever control, the illusion is created that the sound source would be located somewhere else in the room than is actually the case. This special effect is often used in the cinema or at a concert.

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With 3D animations it becomes particularly interesting. To the optical illusion is then namely added a spatial image. The prerequisite is that the sounds are placed exactly in the right place. You feel the resulting impression as even more realistic, and sometimes you can almost no longer distinguish between film and reality.

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The Special McGurk Effect

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Do you know for a fact that you can hear exactly what someone is saying? If you are really so sure, you can try it once with the McGurk effect. This is a very interesting acoustic illusion: an auditory experience is superimposed by the optical perception namely. The decisive factor is always the movement the speaker makes with his mouth. You then actually believe that you are hearing different words. The deposited sound sequence, however, does not change at all.

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With this effect, you find that you can even read lips unconsciously, but for an accurate recognition you need some practice.

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The tinnitus as a delusion

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One of the best known and most unpleasant acoustic illusions is the tinnitus. This is actually pure phantom noises in your ear. You can hear them, but they do not really exist. Tinnitus can be very disturbing for you. Especially when the tinnitus proves to be permanent, it becomes really uncomfortable.

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Triggers for tinnitus include:

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  • accidents
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  • Hearing trauma due to short- or long-term overuse
  • Stress

For tinnitus, different treatment approaches are considered, for example, drug, psychological or physiological therapies.

A hearing aid can also contribute to the successful treatment of your tinnitus.

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