Sound illusions can occur in absolutely healthy people under the influence of stress, excitement, and unusual conditions. In each specific case, psychologists find an appropriate explanation.
These can be sound barriers, or, as scientists call them, sound "mirrors", distortion associated with different sound wavelengths. There are several well-known sound illusions that every healthy person can experience for themselves.
The sound illusion, dubbed "hidden steps," was discovered by Diana Deutsch’s, a professor of psychology, who apparently proves that the human brain can group nearby notes together.
To demonstrate this effect, two melodies are played, increasing and decreasing in tone, while the notes are different for human ears in perception. For example, one ear can hear, as it were, mixed - first the first note of the first melody, then the second note of the second melody.
The brain of most of the listeners groups high and low notes together, therefore, with different ears, a person hears a decreasing, increasing sequence of sounds (with one ear) and vice versa, increasing, decreasing - with the other ear.
The right-hander hears with the right ear first - an increasing tone, the left-hander - the opposite. From all this chaotic set of notes and tones, the brain chooses a suitable melody, which our consciousness perceives with its help (sound perception).
The discovery of the "increasing sequence" or Shepard's paradox belongs to the French composer Jean-Claude Risset, and is expressed in the fact that pairs of notes, following in succession, create an increasing sound illusion (as when the keys on the piano are pressed from left to right).
In reality, there is no increase in tone, and if you play this melody an infinite number of times in a row, then the person will perceive the constant increase in tone, although this cannot be, this is a sound illusion created by the brain "independently".
The sound illusion, called "falling" bells, is that the sounds of the bells heard in the recording "fall" with decreasing pitch.
However, listening attentively, the person realizes that the tone, on the contrary, increases. That is, the starting pitch is lower than the ending.
The sense of the "speeding up" drums illusion is that they actually sound the same, although the tempo seems to be constantly increasing. Listen carefully!
The illusion, called by experts as a "virtual hairdressing salon", is a binaural effect, and consists in the ability of a person and an animal to determine on which side of them the sound source is located due to the presence of two ears, which act as sound receivers (a source located in front or behind, it is determined poorly and inaccurately).
Due to the fact that the sound travels to the ear located closer to its source, a shorter path, sound waves in the ear canals have different phases (the time it takes to pass this phase) and the amplitude (strength) of sound vibrations. Therefore, the perception of sound of different heights will be different. The direction to the sound source for low sounds (up to 1500 vibrations / second) is determined by the human consciousness most accurately and almost completely by the difference in the transit time of a given phase of sound waves.
And for high sounds, due to the fact that the difference in sound strength between the right and left ear is of primary importance, the determination of direction will be less accurate. The ability to determine the direction of sound arises due to the fact that the difference in the phases and intensity of sounds perceived by the ear leads to a difference in impulses that enter the central nervous system from the right and left ear.
No less well-known to specialists is the stereo effect, a kind of sound illusion - "matchbox". To achieve the result of its occurrence, it is imperative to close your eyes.
The paradox called "three notes" was also explored by Diana Deutsch's, in a sound recording you can hear several grouped notes, which each of the listeners perceives differently.
The difference lies in the fact that some perceive them as falling tones, while others - as rising. This phenomenon has been known since ancient times, then it was considered the tricks of the devil.
Phantom melodies are a sound illusion that can be created with the help of some melodies, consisting of quick plays, and very slightly different from each other. When the melodies are played quickly, the brain is able to "select" some individual notes at speed and "compose" them into its own melody.
With a slow loss of the same composition, such a sound illusion does not arise, which is explained by the ability of consciousness to have time to perceive all the correct parts of the losses.
An illustration of this phenomenon is the composition Rustle of Spring, performed quickly, in this case a false melody will appear in the mind, and when played slowly, the sound illusion disappears.
This illusion was first demonstrated by Diana Deutsch of the University of California, San Diego. Writing is like overlapping sequences of repeating words or phrases located at different points in space.
By listening to them, you begin to distinguish certain phrases. Although in fact there are no phrases. Your brain composes them itself, in order to give meaning to meaningless noise.
How young we were .
As people age, they lose the ability to hear high frequencies. This sound can only be heard by those who have not yet celebrated their own majority (although there are exceptions among older people, but they are quite rare) - its frequency is 18,000 Hz (by the way, your dog will definitely hear this sound).
Some teens set this sound to ring a cell phone so only they (and of course their peers) can hear the ringing. In some countries, this sound is played very loudly in places where young people are undesirable.
The story of the giant stones located in Stonehenge (England) is very interesting; they have an amazing ability to create sound illusions that are not mirages of an acoustic nature. The discovery and substantiation of this phenomenon belongs to the American researcher Stephen Waller, a scientist of archaeoacoustics, who conducted research on the acoustics of the famous architectural ensemble, erected in southern England more than 5000 years ago.
If two musicians play the trumpet, standing in the center of this structure, an amazing sound effect arises - in some places around the musicians the sounds of their playing are not heard, observers “hear” the silence. Waller explains this by the fact that sound waves are reflected from the stones and absorb each other, as a result of which a "magic circle" of complete silence is formed around the musicians.
People invited by the researcher to conduct the experiment, blindfolded, stood in the center of this circle, and listened to the play of two trumpeters. Once in the "dead" sound zone, they stopped hearing sounds, and then told that they saw an obstacle (in reality it was absent) between them and the trumpeters.
Sound illusions for mentally ill people
Completely different origins and explanations have sound illusions for mentally ill people. As a rule, sound illusions take the form of shouts, voices and abuse, suspicious (for a sick person) whispers, shots and whole cannonade, singing, orchestral music. Sometimes a patient in an unclear extraneous noise can "hear" separate conversations in which various people take part, sometimes he "recognizes" these voices, sometimes he hears the speech of strangers to him. These sound illusions are "invented" by the sick consciousness, presenting completely extraneous sound stimuli for clear speech.
As in other cases of manifestations of various types of illusions, doctors try to separate sound illusions from auditory hallucinations. In the first case, there is an imaginary erroneous perception by the patient of extraneous noises, and in the second - invented imaginary sounds. And in one, and in another case there is a unifying phenomenon - all "conversations" are, as a rule, accusatory and condemning a sick person.
Rarely, a phenomenon occurs in which sound illusions soothe the patient and persuade him to calm down. Usually, sound illusions intensify in noisy environments, when a large amount of sound and noise provokes the sick person's consciousness to "hear" conversations. In cases of incorrect perception of sounds, the effect of a sound illusion occurs.