- Simultaneous listening of the scale in ascending and descending order:
There are several ways in which people perceive these sounds, but in the most general case they group the highs and lows together. Thus, instead of hearing both scales, a descending and ascending melody is heard in one ear and an ascending and descending melody in the other. In other words, the brain regroups some of the notes in the different ears to form a coherent melody. - Phantom melodies:
Some musical performances consist of fast fragments that change slightly, almost imperceptibly. If they play fast enough, the auditory analyzer selects random notes from those that change and connects them to form a melody. This melody disappears if the music is played more slowly. - Hearing missing bass:
This is the hearing of a missing fundamental frequency due to the auditory analyzer’s interpretation of the other parts of the harmonic order of this frequency higher harmonics. In practice, this effect is used to reproduce bass from compact speakers (on the order of 1 ltr), with which it is impossible to reproduce, for example, 50 Hz with a satisfactory volume. By reproducing a sufficient amount of harmonic frequencies above 150 Hz, the illusion is complete and the listener sometimes wonders where the invisible subwoofer is located. - Falling bells:
This is a paradox in which, when a recording is played, the bells sound as if they are falling into space. When they fall, the pitch is heard decreasing, but in reality the pitch increases and it becomes higher. If this recording is recorded repeatedly, connecting the end to the beginning, you can clearly hear the bell falling when the sound is repeated. This reveals that the opening tone is lower than it is at the end of the sound. - Virtual barber shop:
This is a demonstration of a stereo effect. As you listen to it, you have the feeling that you are in the barber’s chair and the barber is circling around you, clicking the scissors on your hair. As the barber moves to your right, the volume increases slightly in the right channel and decreases in the left. Similarly, the increase in volume creates the impression that the scissors are getting closer to each ear. This sound illusion demonstrates our ability to locate sounds in space, and by comparing the volume in both ears we can determine the distance from which this sound comes. - Phantom phrases:
This demonstration was made at the University of California, San Diego. The record was an overlapping series of repetitive words or phrases located in different places in space. As you listen to them, you begin to choose specific phrases. However, some of the phrases do not really exist. The auditory analyzer in your brain composes them, trying to find meaning in the chaos of words. In fact, you may hear phrases that are related to something that is on your mind, for example, people who are on a diet often hear phrases associated with food. This can sometimes be very annoying. - A tone to shout at teenagers
This is a sinusoidal sound with a frequency of 18,000 Hz. This sound can only be heard by people under the age of 20 (some over the age of 20 can hear them, but these are rare). This is used by some teens as a ringtone on their cell phones, so only they (and others in their age group) can tell if their phone is ringing. As people get older, they start to lose the ability to hear this sound because it is too loud for people over 20. - Surrounding sound:
If two very close tones are reproduced, for example 500 Hz and 500.5 Hz, a beat equal to the difference of 0.5 Hz frequencies occurs. Such a frequency cannot be determined by hearing, but the changing phase difference between the two sounds causes the sensation of a point sound source circling around the listener for a period of 2 seconds. The amplification of the sound causes the imaginary point sound source to approach the listener’s head, while the attenuation of the sound causes it to move away in a spiral trajectory. Perhaps the most interesting thing in this case is that the effect of a sound event in space is reproduced by a single speaker (no pair of speakers is needed to reproduce this sound illusion).
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