Biofeedback device for recognition of .alpha. wave component and muscle potential component

A biofeedback device comprising

• (a) a pair of electrodes on the head skin of a subject for detecting a brain wave potential of a frequency of 8 to 13 Hz including an alpha-wave potential and a brain wave potential of a frequency of more than 13 Hz including a muscle potential,
• (b) a first band-pass filter for extracting from the detected potentials a wave component of the frequency of 8 to 13 Hz,
• (c) a second band-pass filter for extracting from the detected potentials a wave component of the frequency of more than 13 Hz,
• (d) a first half-wave rectifier for cutting off the negative component of the wave component extracted by the first band-pass filter,
• (e) a second half-wave rectifier for cutting off the negative component of the wave component extracted by the second band-pass filter,
• (f) a first oscillator for producing a sound of the frequency of 800 Hz and a strength proportional to that of the wave component from the first rectifier,
• (g) a second oscillator for producing a sound of the frequency of 1,600 Hz and a strength proportional to that of the wave component from the second rectifier, and
• (h) a pair of earphones guiding the oscillated sounds simultaneously to the ears of the subject, one of the earphones guiding the sound of the frequency of 800 Hz produced by the first oscillator to one of the ears and another one of the earphones guiding the sound of the frequency of 1600 Hz produced by the second oscillator to the other ear, thereby to permit the subject to discern his own mental state from the strength of the sounds of the frequencies of 800 and 1600 Hz.