Alpha and Theta Response to a Programmed Auditory Stimulus: Acoustic Brain Research Tapes and Entrainment
Bruce Harrah-Conforth, PhD Indiana University
SYNOPSIS OF STUDY
As early as 1934 Adrian and Matthews showed that the resting rhythms of the brain could be made to assume the frequency of a photic stimulus (“entrainment”). It was not until 1960, however, that any similar tests using an auditory stimulus were done (Neher: 1960).
In recent years a growing number of tapes and devices have been produced which claim to use the principle of entrainment for the purposes of enhancing performance, stress reduction, creativity, and a host of other byproducts.
The aim of this study was to ascertain and analyze the efficacy of various “brain entrainment” audio tapes produced by Acoustic Brain Research. These tapes, it is claimed, assist in stimulating alpha and theta brain waves in test subjects by alerting the Reticular Activating System (RAS) to incoming signals and activating the cerebral cortex.
Techniques by which ABR claims to facilitate such changes in the brain are: Threshold Electronic Pulsations, frequency modulations, musical patterning, tonal architecture and hemispheric spanning.
Methods and Materials
The subjects were 15 volunteers, 6 females and 9 males, aged 25 – 38, all of whom were considered to be in good health. The test environment consisted of having the subjects lie on a bed in a dark room, with their eyes shut throughout the session. Three electrodes were placed “left occipital to left parietal.” A baseline reading was established with regard to the normal relaxed state of each subject.
The subject was then equipped with a set of stereo headphones through which four different ABR tapes were played: Sound Meditation, Wave Form, Creativity and Intuition, and Movement with Body Sync, as well as four tapes of pink noise not by ABR. The average time of each tape was 20 minutes. During each session the subject’s production of Beta, Alpha, and Theta waves were monitored. Sensitivity settings during the tests ran from 3 uvpp through 100 uvpp. Brain wave readings were also taken at 5 minute intervals following the stimulation for a total period of 20 minutes.
The ABR tapes used are described by ABR in the following manner:
The Wave Form tape is designed with the intent of producing the theta state for relaxation. The tone generated is based on the Principle of the Perfect Harmonic Fifth.
Designed to be a meditative experience the Sound Meditation tape utilizes the Pythagorean (pure) tone, Mongolian chanting, as well as Tibetan bowls and bells.
Creativity and Intuition
This tape utilizes complex tonal matrices and cross lateral stimulation as well as including subliminal messages designed to increase creativity.
Movement with Brain Sync
ABR claims that this tape facilitates brain synchronization and its subliminal messages aid on the clearance of emotional energies and forgiveness. The sounds used consist of oceans, birds, whales, and soothing music.
As expected, subjects produced a “classic” alpha driving response when they closed their eyes, even though no auditory stimulus was present. A baseline was then established for their resting brain. Immediate visual and auditory indications showed that the ABR tapes increased beta activity, decreased alpha activity, and increased theta action.
Influence of Pink Noise
There was no significant difference between resting wave production and wave production under pink noise stimulation (0.05).
Influence of ABR tapes
All ABR tapes produced an initial decrease of the Alpha band, while two ABR tapes (Sound Meditation and Wave Form) produced increases of the Theta band.
In order to compare each subject’s susceptibility to auditory stimulation the significance of ABR stimulation was only considered if it was more than >0.05 above the noise response. The findings seemed to indicate a link between an altered EEG response and ABR tapes that could not be evidenced with the pink noise alone.
Four ABR tapes were tested. All four ABR tapes produced significant changes in the theta band in 19 out of 32 (59%) sensitivity frequencies. Two ABR tapes succeeded in this regard more than 68% of the test time (13 out of 16). All four ABR tapes showed alpha attenuation (20 out of 32 or 62%), and three tapes showed beta enhancement (9 out of 32 or 28%).
In comparison, the test tape, which included only pink noise as its sound source, showed no significant theta enhancement, some alpha enhancement (37%), and no beta change.
It is suggested that in this test with these subjects the ABR tapes did assist in the alteration of the subjects’ brain wave bands.
Perhaps the most difficult task to undertake is to assign psychological meaning to physiological change. Although the actual meanings of brain waves are not understood, research has permitted a general consensus to be adopted with regard to these states. Cade (1979), building upon the work of Lesh (1970), was able to formulate a relationship between objective and subjective states. His findings indicated, and have been verified by other researchers, that various brain wave states correspond to various psychological ones.
The beta state (13-30 Hz) corresponds to our normal waking consciousness.
The alpha state (8-13 Hz), appears to be the equivalent of relaxation and concentration.
Theta waves (5-7 Hz), are such that they seem to reflect a deeply internalized state, deep relaxation, a sense of quieted emotions, and the production of hypnogogic imagery.
Delta waves (.5-4 Hz), are those which are usually associated with sleep or other similarly unconscious states.
The relationship of test subject’s subjective reporting of their experiences using the ABR tapes and the pink noise tapes to their brain wave indications appears to verify the findings of researchers such as those mentioned above.
While little relaxation occurred during the pink noise sessions, subjects reported feeling marked changes in their bodily sensations during the ABR Wave Form and Sound Meditation tapes. This seems to correspond to an increased production of theta waves and an attenuation of alpha waves experienced by subjects while using these tapes.
Among the subject’s comments were such typical descriptions as “I lost all sense of my body,” “I felt like I was flying,” “I was deeply relaxed,” I felt like I was out of my body,” etc. There appeared to be no significant difference in reports by either sex or age.
If these findings are substantiated by future research, it follows that the ABR tapes will be shown to be effective means by which a variety of psycho-physiological conditions (stress, anxiety, self-esteem, etc.) may be altered.
While no cause and effect is implied in this research, the high incidence of similar reports among subjects seems to indicate that further studies are necessary to investigate this realm.
No theories about alpha or theta activity can be inferred from this study, but the study of ABR tapes to both subjective and objective analysis should prove rewarding.
Adrian, E.D. and B.H.C. Matthews. 1934. “The Berger Rhythm: potential changes from the occipital lobes in man,” in Brain Vol. 57, pp. 355384.
Cade, C. Maxwell, and Nona Coxhead. 1979. The Awakened Mind Biofeedback and the Development of Higher States of Awareness. New York: Delacorte Press.
Neher, A. 1961. “Auditory Driving observed with Scalp Electrodes in Normal Subjects,” in Journal of Electroencephalography and Clinical Neurophysiology Vol. 13. pp. 449-451.
Lesh, Terry V. 1970. “Zen Meditators and the Development of Empathy in Counselors,” in Aldine Annual.