Patent No. 3753433 Electroencephalophone and feedback system

 

Patent No. 3753433  Electroencephalophone and feedback system (Bakerich, et al., Aug 21, 1973)

Abstract

An electroencephalophone which is battery operated and completely self-contained in a headset to be worn by the user and having a plurality of scalp electrodes carried on flexible leads permitting placement of the electrodes on the user's head when the headset is mounted thereon and having an electronic circuit and transducer for converting brain wave signals picked up by the electrodes into recognizable audio tones enabling the user to listen to his own brain wave generation. The scalp electrode signals are amplified and chopped by an audible oscillator signal the frequency of which is controlled by the scalp electrode signals. The resulting combined amplitude and frequency modulation of the audible generator tone provides a distinctive sound for brain wave recognition.

Notes:

Description

The invention relates to electroencephalographs in which the EEG output is converted into an audio signal enabling audio study and analysis of the type and character of brain waves being generated.

Researchers and investigators have found that there is a relationship between subjective states of mind and observable brain wave activity as seen with the aid of an electroencephalograph (EEG). Anxiety, focused attention, relaxed inattention, the various stages of sleep, and meditation appear to have correlating brain wave patterns. Anxiety, focused attention and active thought tend to produce beta waves considered as those having a frequency greater than about 13 Hz. Relaxed, alert inattention, with the eyes closed or at least defocused with no patterned visual input, will tend to produce alpha waves considered as those having frequencies from about 8 Hz to about 13 Hz. Deeper states of relaxation, meditation, sleep will involve lower frequencies in the theta and delta ranges considered as between about 4 Hz to about 8 Hz, and below 4 Hz respectively. The electroencephalograph thus provides an important research, educational, and training tool to aid doctors, investigators and patients in better understanding and achieving various states of mind. For example, there has been a continuing search for a means of achieving a peaceful state of mind. Various meditative techniques, some very ancient and some quite new, have been and are being used. However, these techniques have a common drawback in that they do not provide an immediate feedback as to the progress that the individual is making. It is known that a peaceful, meditative state of mind is accompanied by the production of alpha waves and experimental studies have shown that a person, given appropriate feedback information as to the brain waves he is generating, can learn to turn on the alpha rhythm at will.

Various forms of feedback information have been proposed. It has been found that the sense of hearing is far superior to the sense of sight as a harmonic analyzer, and is therefore more adept at detecting and analyzing patterns of activity. Stewart, Belcher and Morris, Auditory Analysis of Electroencephalogram: Electroencephalophony, Encephalography and Clinical Neurophysiology, Volume II, pages 161-164 (May, 1959 ed.). The practical difficulty with listening to brain wave patterns directly is that the clinically interesting frequencies are in the sub-audible range. The brain's electrical output must therefore be transformed before the analytical merits of the human auditory system can be utilzed. The mentioned publication describes several methods by which this can be accomplished and suggests a combined amplitude and frequency modulation of an audio carrier by the brain waves as providing a highly satisfactory method.

One of the disadvantages of EEG equipment heretofore available for research, study and training has been the high cost of such equipment and accordingly the investigations have so far been conducted in the research settings of major medical laboratories. Circuitry and components heretofore developed and used have been complex and relatively large and cumbersome. An object of the present invention is to provide an electroencephalograph feedback system of the character described in which the very best of earlier techniques are used, e.g., amplitude and frequency modulation, while at the same time circuitry and components have been modified and evolved to provide a small inexpensive yet completely effective instrument.

Another object of the present invention is to provide an electroencephalophone of the character described which is battery operated and completely self-contained whereby all of the apparatus is exclusively and comfortably worn on the head of the user without any trailing wires and thus affording the user mobility, convenience and safety from electric shock.

A further object of the present invention is to provide an electroencephalophone of the character above which may be mounted on the head of the user with ease and facility, is easy to operate, and in which the desired brain waves are amplified and raised in pitch to a pleasant comfortable audio frequency, substantially free of background noise.

Still another object of the present invention is to provide an extremely small, battery operated EEG circuit combined with an electroencephalophone and output circuit providing FM telemetry data and a direct EEG signal, the total system being sufficiently small and light in weight to be comfortably worn on the head of the user.

Still a further object of the present invention is to provide an electroencephalophone of the character above which will provide dependable substantially carefree service over a long period of use.

The invention possesses other objects and features of advantage, some of which of the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of this specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.