The method for strengthening the emotional perception of rhythmic sounds
The presented equipment analyzes the rhythm of the recorded music on its playing-back and selects out the harmonic frequency in the infrasonic range. The signal of the selected frequency is transferred to a human by vibration and flashing light (1). Infrasonic signals change the fixed frequency of electric activity of the brain (2). However, in absence of synchronization with music, such signals are perceived as an extraneous noise. Acoustic infrasonic accompaniment upon taking into account the biophysical mechanisms of perception strengthens the emotional perception of the music (3). Generation of infrasonic vibrations in air requires cumbersome equipment. The simplest method is transmission of vibrations through solid and elastic bodies. If an eccentric cam or a crank mechanism is used for generation of vibration, reduction of power consumption, as compared to usual acoustic systems, takes place.
Description of the first experimental research
The experiment was carried out in an open air party. Music of Psytrans style is used for the accompaniment. The acoustic signal, via the microphone and the analogous filter is applied to the input of the microcontroller that selects the rhythm and multiplies the frequency by 4. The average value of the frequency of rhythm is 2.4 Hz. The average frequency of the infrasonic signal is 9.6 Hz (the brain's alpha rhythm). The microcontroller controls operation of the stroboscopes and the vibrator; in addition, it generates a signal for synchronization of changes of images on the video display. The vibrator in a waterproof case is buried in the ground under the dancing. The vibrator consists of an engine and two flywheels rotating in opposite directions. Ground absorbs the noise caused by the engine's operation and infrasonic vibrations are sent on the surface. The first stroboscope equipped with UV diodes is directed to fluorescence decorations. Two xenon stroboscopes operate with a 50%-shift of their periods. An object placed between the xenon stroboscopes is lighted by the xenon stroboscopes in rotation from the both sides with the frequency of alpha rhythm.
Testing of the system in absence of musical accompaniment showed that the changes of the emotional status felt by the persons under the testing appear approximately after 10 minutes. However, the said effect is weak. Some persons feel only an irritation caused by the vibration and the flashing. A regular using the system on holidays strengthens the emotions. The vibrations of the ground are similar to rhythmic motions of the persons dancing on it. Besides, the vibrations of the ground are subjectively perceived as an impact of more powerful acoustic system as compared to the impact of the real system. In addition to other elements, such as high quality acoustic properties, decorations, light effects and so on, the system considerably supplements the effect of perception. In this experiment, the power of the vibrator is low and its effect is felt in the best way while sitting on the ground close to it.
Another generator of infrasonic fluctuations
The purpose of the developed device is intensifying the emotional perception of an acoustic signal by additional tactile and visual sensations. Close to a powerful low-frequency dynamic speaker, a human body feels vibrations of air and this effect considerably intensifies perception of music. The below-described device generates air vibrations synchronized with the acoustic signal in the infrasonic range. The amplitude of such vibrations is larger as compared to the amplitude of the ones generated by a low-frequency dynamic speaker, so they cause a sensation that the acoustic system is more powerful that it is in realty. A tactile sensation of the air flow is possible in a close distance from the device. However, in case of operation of a smoke generator or waving of flags, the air vibrations will be remarkable in a larger distance. The device consists of a fan with a variable-pitch prop fixed on it. Variation of the pitch is bound with the amplitude of the acoustic signal in a certain frequency range. Usually, the bass range frequency is singled out; however, vocal range frequencies or high frequencies may be singled out, if they express better the acoustic accents in music. For generating powerful infrasonic vibrations, the fan should rotate in a special hole in the wall between two rooms; however, it is not required for decorative effect, so in such a case, the fan may be installed in an open place. Operation of the experimental device is shown in the video:
1. Patent LT5889
2. The Paper "The Response of the Electric Activity of the Brain to Flashing Light with the Frequency of Alpha Rhythm" by N.N.Danilova published in the USSR Academy of Sciences "Journal of the Higher Nervous Activity", Vol XI, issue 1.
3. Patent RU2284584 "The Method of Transferring an Acoustic Signal to a Listener and the Device for its Realization"