About Binaural Beats

Binaural beats is a brain response when presented with two slightly different tonal changes in a stereo situation. When a person is presented with the two different tones - the brain produces a response (binaural beat) that produces an altered state in brainwaves and therefore a hypnotic trance or super learning type environment.

What are Binaural Beats (Detailed Definition)
Binaural beats are auditory brainstem responses which originate in the superior olivary nucleus of each brain hemisphere. They result from two different auditory impulses or sounds, heard from opposite ears. This binaural beat is consciously heard as the human hearing range is from 20-20,000 Hz. Rather it is perceived as an auditory beat and theoretically is being used coach certain brain rhythms from what is called the frequency-following response (the tendency for the brain to resonate at the frequency of an external stimulus).

The brain produces a phenomenon resulting in low-frequency pulsations in the loudness and sound localization of a perceived sound when two tones at slightly different frequencies are presented separately, one to each of a subject's ears, using stereo headphones. A beating tone will be perceived, as if the two tones mixed naturally, out of the brain. The frequency of the tones must be below about 1,000 to 1,500 hertz for the beating to be heard. The difference between the two frequencies must be small (below about 30 Hz) for the effect to occur; otherwise, the two tones will be heard separately and no beat will be perceived.

Binaural beats are of interest to neurophysiologists investigating the sense of hearing. Second, binaural beats reportedly influence the brain in more subtle ways through the entrainment of brainwaves and can be used to reduce anxiety and provide other health benefits such as control over pain.


History
Heinrich Wilhelm Dove discovered binaural beats in 1839. While research about them continued after that, the subject remained something of a scientific curiosity until 134 years later, with the publishing of Gerald Oster's article "Auditory Beats in the Brain" (Scientific American, 1973). Oster's article identified and assembled the scattered islands of relevant research since Dove, offering tremendous fresh insight (and new laboratory findings) to research on binaural beats.

Oster also considered binaural beats to be a potentially useful medical diagnostic tool, not merely for finding and assessing auditory impairments, but also for more general neurological conditions. (Binaural beats involve different neurological pathways than ordinary auditory processing.) For example, Oster found that a number of his subjects that could not perceive binaural beats suffered from Parkinson's disease. In one particular case, Oster was able to follow the subject through a week-long treatment of Parkinson's disease; at the outset the patient could not perceive binaural beats; but by the end of the week of treatment, the patient was able to hear them.

In corroborating an earlier study, Oster also reported gender differences in the perception of beats. Specifically, women seemed to experience two separate peaks in their ability to perceive binaural beats- peaks possibly correlating with specific points in the menstrual cycle (onset of menstruation and approx. 15 after). This data led Oster to wonder if binaural beats could be used as a tool for measuring relative levels of estrogen.

The effects of binaural beats on consciousness were first examined by physicist Thomas Campbell and electrical engineer Dennis Mennerich, who under the direction of Robert Monroe sought to reproduce a subjective impression of 4Hz oscillation that they associated with out-of-body experience. On the strength of their findings, Monroe created the binaural-beat technology self-development industry by forming The Monroe Institute, now a charitable binaural research and education organization.

Physiology
The sensation of binaural beats is believed to originate in the superior olivary nucleus, a part of the brain stem. They appear to be related to the brain's ability to locate the sources of sounds in three dimensions and to track moving sounds, which also involves inferior colliculus (IC) neurons. Regarding entrainment, the study of rhythmicity provides insights into the understanding of temporal information processing in the human brain. Auditory rhythms rapidly entrain motor responses into stable steady synchronization states below and above conscious perception thresholds. Activated regions include primary sensorimotor and cingulate areas, bilateral opercular premotor areas, bilateral SII, ventral prefrontal cortex, and, subcortically, anterior insula, putamen, and thalamus. Within the cerebellum, vermal regions and anterior hemispheres ipsilateral to the movement became significantly activated. Tracking temporal modulations additionally activated predominantly right prefrontal, anterior cingulate, and intraparietal regions as well as posterior cerebellar hemispheres. A study of aphasic subjects who had a severe stroke versus normal subjects showed that the aphasic subject could not hear the binaural beats whereas the normal subjects could.

When the perceived beat frequency corresponds to the delta, theta, alpha, beta, or gamma range of brainwave frequencies, the brainwaves entrain to or move towards the beat frequency. For example, if a 315 Hz sine wave is played into the right ear and a 325 Hz one into the left ear, the brain is entrained towards the beat frequency 10 Hz, in the alpha range. Since alpha range is associated with relaxation, this has a relaxing effect or if in the beta range, more alertness. An experiment with binaural sound stimulation using beat frequencies in the Beta range on some participants and Delta/Theta range in other participants, found better vigilance performance and mood in those on the awake alert state of Beta range stimulation.

Binaural beat stimulation has been used fairly extensively to induce a variety of states of consciousness, and there has been some work done in regards to the effects of these stimuli on relaxation, focus, attention, and states of consciousness

Frequency range	Name	Usually associated with:
> 40 Hz	Gamma waves	Higher mental activity, including perception, problem solving, fear, and consciousness
13–39 Hz	Beta waves	Active, busy or anxious thinking and active concentration, arousal, cognition
7–13 Hz	Alpha waves	Relaxation (while awake), pre-sleep and pre-wake drowsiness
4–7 Hz	Theta waves	Dreams, deep meditation, REM sleep
< 4 Hz	Delta waves	Deep dreamless sleep, loss of body awareness

(The precise boundaries between ranges vary among definitions, and there is no universally accepted standard.)

The dominant frequency determines your current state. For example, if in someone's brain alpha waves are dominating, they are in the alpha state (this happens when one is relaxed but awake). However, also other frequencies will be present, albeit with smaller amplitudes.

The brain entraining is more effective if the entraining frequency is close to the user's starting dominant frequency. Therefore, it is suggested to start with a frequency near to one's current dominant frequency (likely to be about 20 Hz or less for a waking person), and then slowly decreasing it towards the desired frequency.

Some people find pure sine waves unpleasant, so a pink noise or another background (e.g. natural sounds such as river noises) can also be mixed with them. In addition to that, as long as the beat is audible, increasing the volume should not necessarily improve the effectiveness, therefore using a low volume is usually suggested. One theory is to reduce the volume so low that the beating should not even be clearly audible, but this does not seem to be the case .

How It Works On The Brain
When signals of two different frequencies (sounds) are presented, one to each ear, the brain detects phase differences between these signals. The brain processes this anomalous information differently when these phase differences are heard with stereo headphones or speakers. A perceptual integration of the two signals in perceived in the brain, producing the sensation of a third "beat". The difference between the signals waxes and wanes (this is the "wavy" sound heard in the hypnotic sessions) as the two stereo sounds mesh in and out of phase. The binaural beat is perceived as a fluctuating rhythm at the frequency of the difference between the two auditory inputs.

How It Creates a Hypnotic Response
Binaural beats can easily be heard at the low frequencies (< 30 Hz) that are characteristic of the EEG spectrum (Oster, 1973). This perceptual phenomenon of binaural beating and the objective measurement of the frequency-following response (Hink, Kodera, Yamada, Kaga, & Suzuki, 1980) suggest conditions which generate brain waves activity and altered states of consciousness (hypnotic trance).

There are a growing amount of research efforts reporting changes in consciousness associated with binaural-beats. "The subjective effect of listening to binaural beats may be relaxing or stimulating, depending on the frequency of the binaural-beat stimulation" (Owens & Atwater, 1995). Binaural beats in the delta (1 to 4 Hz) and theta (4 to 8 Hz) ranges have been associated with reports of relaxed, meditative, and creative states (Hiew, 1995), and used as an aid to falling asleep. Binaural beats in the alpha frequencies (8 to 12 Hz) have increased alpha brain waves (Foster, 1990) and binaural beats in the beta frequencies (typically 16 to 24 Hz) have been associated with reports of increased concentration or alertness (Monroe, 1985) and improved memory (Kennerly, 1994).Mind-Fit uses the differing rates of Binaural beat stimulation during the induction and therapy parts of its sessions to aid in the progressive relaxation acquired when entering the Hypnotic state.

Hear how Binaural Beats sound when encoded into Music
Binaural beats can be heard within a music track because each channel has been altered to produce a sound with a difference reflecting the desired frequency. Following is a sample to show you the effect. First you will hear 20 seconds of a piece of music, followed by the same piece encoded with binaural beats. You should hear a slight wavy sound effect.

Click the image to play the sound