Rhythmic Sensory Stimulation (RSS)
Current research indicates that sound stimulation at low frequencies stimulates or drives a brain wave response at the stimulation frequency. For example, stimulation at 40Hz will increase electro-potential power of steady state brain activity at 40Hz. Brain connectivity seems strongly related to 40Hz activity. Several studies recently completed show a strong positive effect on Fibromyalgia from 40Hz stimulation as well as on Alzheimer's Disease. (See Globe & Mail article)
RSS is the over-arching category for the following three therapies as well as for Rhythmic Auditory Stimulation.
Low Frequency Sound Therapy. The application of sinewave sound in the 27 – 120hz range to the human body for therapeutic purposes. Effects are essentially the result of two mechanisms: (1) physical, through muscular and cellular means, and (2) neurological, through sensory-based brainwave entrainment (see entry). At the physical level sound vibration is sensed by tactile receptors in the outer skin (Merkel disks – vibratory strength), inner skin (Meisner corpuscles - vibratory frequency) and in deeper tissues (Pacini corpuscles - acceleration). To avoid numbing of these sensors, LFST is usually constantly varied in amplitude (power pulsation) and/or frequency (scanning). The physical therapeutic effect is obtained at a cellular and lymphatic level due to increased fluid and cellular waste transport, increased cellular metabolism, and increased blood circulation, as well as muscular relaxation due to a resonance response. Within the brain, vibration hypothetically enhances flow of cerebro-spinal fluid and speeds removal of metabolic waste. Although less explored and often not differentiated in research, considerable health effect of LFST may result at the neurologic level from brainwave entrainment, especially through prolonged application of a single frequency (e.g., 40hz). Contraindications include acute inflammatory conditions, pregnancy, pacemakers, hypotension, and thrombosis. LFST device producers include Sound Oasis (see link below).
Vibroacoustic Therapy. An approach to low frequency sound therapy developed by Olav Skille in Norway between 1968 and 1980 and first applied to developmentally delayed children with a prototype in 1980. It uses sinusoidal sound between 30 and 120hz with particular emphasis on 40, 52, 68, and 86hz. Treatment involves application of a single frequency that is modulated with a steady rise and fall of amplitude at a rate of about 6 to 8 seconds from peak to peak. A noteworthy application of this method in research was done by Wigram (1996).
Physioacoustic Method. An approach to low frequency sound therapy developed by Petri Lehikoinen in Helsinki, Finland. It uses low frequency sinusoidal sound (27 – 113 hz) featuring slow power pulsation to prevent muscle contraction, frequency scanning to treat muscles with their particular resonance frequency, and at times directional movement of the sound (Lehikoinen, 1997). Lehikoinen developed the Next Wave chair system that was FDA and BSI approved in the early 1990’s for three claims related to Physioacoustic therapy: increased circulation, decreased pain, and increased mobility.
Driving a Brain Response with Sound