Binaural beats

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Audio sample: left channel 440 Hz, right channel 430 Hz. The audio sample should be heard with headphones so that the individual ears only perceive the intended channel

Binaural beats (binaural: Latin : with both ears ) are perceptions that are inaudible to third parties and that are felt when sound with slightly different frequencies is fed directly to both ears .

Physiological background

Position of the nuclei olivaris superior (labeled "Superior olivary nucleus")

Binaural beats are created as a sensory impression when the hearing is presented with a separate tone with a slightly different frequency in each ear. A new and pulsating tone then arises in the brain, the frequency of which is roughly the mean of the two initial tones. The frequency with which the pulses occur results from the frequency difference between the two initial tones. In analogy to beating , differences in loudness in the tone are responsible for the pulsating character. Unlike beats, binaural beats are not created by superimposing sound waves.

Researchers suspect the origin of the binaural beats in the auditory pathway , especially in the nucleus olivaris superior, part of the brain stem. Its neurons are involved in the localization of sound sources by evaluating differences in transit time and level between the two ears.

Example: If you hear a frequency of 440 Hz in the left ear and a frequency of 430 Hz in the right ear, a tone with an average frequency of 435 Hz is generated in the brain. The binaural beats are then perceived with a frequency of 10 Hz. In order to be able to perceive a beat, the carrier frequencies must be below 1500  Hz . The difference between the frequencies for the left and right ear must not be greater than 30 Hz, otherwise two different tones will be heard.

Discovery and Exploration

The German physicist Heinrich Wilhelm Dove is considered to be the discoverer of binaural beats in 1839 . He found that beats appear to be heard when two slightly different tones are applied to the left and right ears separately but simultaneously. Dove came to the realization that the perceived beats must arise exclusively in the auditory system, as there was no acoustic mixing. He suspected that the beats originate in the part of the brain that is responsible for binaural (stereophonic) hearing.

In the following years the subject was picked up sporadically, but for a long time it retained the status of a physical curiosity . It was not until Gerald Oster , a biophysicist at the Mount Sinai School of Medicine in New York, recognized the potential and possibilities that binaural beats open up. In 1973 he published an article in Scientific American , where he brought together the various research results of the past 134 years, arranged them and, based on them, presented his own. So he found z. B. found out that for the perception of the binaural beats the carrier frequencies must be below 1500 Hz. The difference between the carrier frequencies for the left and right ears must not be greater than 30 Hz, as otherwise two different tones will be perceived.

Oster saw the areas of application of binaural beats both in research and in the medical field:

  • For research, they were an important instrument to analyze the neural processes of hearing, to investigate spatial hearing and e.g. B. to find out how a single tone can be heard from a mixture of many tones ( cocktail party effect ).
  • In the medical field, Oster thought it was a suitable diagnostic tool for examining impaired hearing.
But he also found that they can be used for ailments that have nothing to do with hearing. He found that shortly before Parkinson's disease began, the ability to hear binaural beats declined significantly. In a special case he was able to accompany a Parkinson's patient for many weeks and document that the ability to hear binaural beats increased again under the medication .
He also observed gender-specific differences in the perception of binaural beats. In women, there were two peak values ​​in the perception of the binaural beats, depending on their menstrual cycle , at the beginning and after around 15 days. These data prompted Oster to wonder whether binaural beats could be used as a measuring instrument for estrogen levels .

A significant result of Oster's research was the finding that a binaural beat is also perceived when a carrier frequency is below the human perceptibility threshold, or when both carrier frequencies are so quiet that the human ear apparently no longer perceives them. These research results led Oster to believe that the binaural beats originate in a different way than the sounds we otherwise hear. The effect of binaural beats only occurs when listening to both ears and arises in the brain as a result of the interaction of perceptions.

Possible effects on well-being

The interest in binaural beats can be divided into three categories:

  1. They are used in neurophysiology to research the sense of hearing .
  2. Neurophysiologically, their influence on the processes in the brain is also researched.
  3. They are used in certain methods with the aim of stimulating the brain waves to promote relaxation , sleep , meditation or concentration .

Binaural beats can affect brain waves and also stimulate those areas of the brain that are not associated with hearing. Measurable effects were found in various studies.

With the help of electroencephalography , different states of consciousness can be assigned different frequency bands of electrical impulses in the brain. A sleeping person's brain waves show different frequencies than when they are awake. Most of these frequencies are below the perception limit of the hearing sense of approx. 20 Hz, so they cannot be perceived or influenced directly. With the help of binaural beats, however, such frequencies can be generated virtually in the brain.

Depending on which state of consciousness is to be reached, the brain is offered one of the five neurologically relevant frequency ranges:

As EEG measurements have shown, the brain is made to approach this offered frequency. This process is known as entrainment or also as brain wave synchronization and neural entrainment. The brain exhibits the ability to naturally synchronize its endogenous rhythms with the rhythm of periodic external auditory, visual, or tactile stimuli.

Entrainment is more effective if the perceived frequency of the binaural beats is close to the prevailing brain frequency (around 20 Hz during the day) and then e.g. B. is slowly lowered for a relaxed state.

Many people find the sound of pure sinus tones uncomfortable, which is why the binaural beats are usually embedded in carrier sounds such as natural sounds or harmonic compositions. Binaural beats are used for deep relaxation in the hemispherical synchronization method and in mind machines.

literature

  • Heinrich Wilhelm Dove ao: acoustics, theoretical optics, meteorology. In: Repertory of Physics. 3, 1839.
  • G. Oster: Auditory beats in the brain . In: Scientific American. Volume 229, Number 4, October 1973, pp. 94-102. PMID 4727697 .
  • Osamu Yamada, Hitoshi Yamane, Kazuoki Kodera: Simultaneous recordings of the brain stem response and the frequency-following response to low-frequency tone. In: Electroencephalography and Clinical Neurophysiology. 43, 1977, pp. 362-370, doi: 10.1016 / 0013-4694 (77) 90259-0 .
  • George M Gerken, George Moushegian, Robert D Stillman, Allen L Rupert: Human frequency-following responses to monaural and binaural stimuli. In: Electroencephalography and Clinical Neurophysiology. 38, 1975, pp. 379-386, doi: 10.1016 / 0013-4694 (75) 90262-X .
  • James D Lane, Stefan J Kasian, Justine E Owens, Gail R Marsh: Binaural Auditory Beats Affect Vigilance Performance and Mood . In: Physiology & Behavior. 63, 1998, pp. 249-252, doi: 10.1016 / S0031-9384 (97) 00436-8 .
  • Christina F. Lavallee, Stanley A. Koren, Michael A. Persinger: A Quantitative Electroencephalographic Study of Meditation and Binaural Beat Entrainment. In: The Journal of Alternative and Complementary Medicine. 17, 2011, pp. 351-355, doi: 10.1089 / acm.2009.0691 .
  • Sebastian Rossböck: Binaural Beats . Thesis. University of Vienna, 2013.
  • PA McConnell, B. Froeliger, EL Garland, JC Ives, GA Sforzo: Auditory driving of the autonomic nervous system: Listening to theta-frequency binaural beats post-exercise increases parasympathetic activation and sympathetic withdrawal. In: Frontiers in psychology. Volume 5, 2014, p. 1248, doi: 10.3389 / fpsyg.2014.01248 . PMID 25452734 , PMC 4231835 (free full text).
  • L. Chaieb, EC Wilpert, TP Reber, J. Fell: Auditory beat stimulation and its effects on cognition and mood States. In: Frontiers in psychiatry. Volume 6, 2015, p. 70, doi: 10.3389 / fpsyt.2015.00070 . PMID 26029120 , PMC 4428073 (free full text) (review).

Programs

  • SBaGen : free, command line based binaural beats generator for Windows, OSX and Linux.
  • Gnaural and Gnaural for Android : free, graphic interface-based binaural beats generator for Windows, OSX, Linux and Android.
  • I-Doser : proprietary binaural beats generator for Windows, OS X, iOS and Android.

Web links

Individual evidence

  1. ↑ Binaural Beats . In: Encyclopaedia Britannica .
  2. ^ MW Spitzer, MN Semple: Transformation of binaural response properties in the ascending auditory pathway: influence of time-varying interaural phase disparity. In: Journal of neurophysiology. Volume 80, Number 6, December 1998, pp. 3062-3076. PMID 9862906 .
  3. ^ Heinrich Wilhelm Dove ao: acoustics, theoretical optics, meteorology. In: Repertory of Physics. Volume 3, 1839, p. 404 in the Google book search
  4. ^ G. Oster: Auditory beats in the brain. In: Scientific American . 229 (4), Oct 1973, pp. 94-102.
  5. ^ MH Thaut: Neural basis of rhythmic timing networks in the human brain. In: Annals of the New York Academy of Sciences. Volume 999, November 2003, pp. 364-373. PMID 14681157 (Review).
  6. ↑ PA McConnell, B. Froeliger, EL Garland, JC Ives, GA Sforzo: Auditory driving of the autonomic nervous system: Listening to theta-frequency binaural beats post-exercise increases parasympathetic activation and sympathetic withdrawal. In: Frontiers in psychology. Volume 5, 2014, p. 1248, doi: 10.3389 / fpsyg.2014.01248 . PMID 25452734 , PMC 4231835 (free full text).
  7. ^ V. Abeln, J. Kleinert, HK Strüder, S. Schneider: Brainwave entrainment for better sleep and post-sleep state of young elite soccer players - a pilot study. In: European journal of sport science. Volume 14, number 5, 2014, pp. 393-402, doi: 10.1080 / 17461391.2013.819384 . PMID 23862643 .
  8. ↑ SA Reedijk, A. Bolder, B. Hommel: The impact of binaural beats on creativity. In: Front Hum Neurosci. 7, 14 Nov 2013, p. 786.
  9. ↑ CF Lavallee, SA Koren, MA Persinger: A quantitative electroencephalographic study of meditation and binaural beat entrainment. In: Journal of alternative and complementary medicine. Volume 17, Number 4, April 2011, pp. 351-355, doi: 10.1089 / acm.2009.0691 . PMID 21480784 .
  10. ↑ R. Padmanabhan, AJ Hildreth, D. Laws: A prospective, randomized, controlled study examining binaural beat audio and pre-operative anxiety in patients undergoing general anesthesia for day case surgery. In: Anaesthesia. Volume 60, Number 9, September 2005, pp. 874-877, doi: 10.1111 / j.1365-2044.2005.04287.x . PMID 16115248 .
  11. ↑ LJ Rogers, DO Walter: Methods for finding single generators, with application to auditory driving of the human EEG by complex stimuli. In: Journal of neuroscience methods. Volume 4, Number 3, October 1981, pp. 257-265. PMID 7300432 .
  12. ^ RA Dobie et al .: Binaural interaction in human auditory evoked potentials. In: Electroencephalography and clinical neurophysiology. 49 (3-4), Aug 1980, pp. 303-313.
  13. ↑ GM Gerken, G. Moushegian, RD Stillman, AL Rupert: Human frequency-following responses to monaural and binaural stimuli. In: Electroencephalography and clinical neurophysiology. Volume 38, Number 4, April 1975, pp. 379-386. PMID 46818 .