Rhythm as Trance-Induction Technique
I divide the rhythmic stimulation of trance in three categories: body rhythm, acustic and optical rhythms. Each of these will be treated here. Please note that rhythmical trance induction can provoke epileptic states. If you have any epileptic disease, then keep of from trance-induction by rhythmic methods.
The body-rhythms inducing trance-states
Generally there are the dance and the shaking or swaying of the body mentioned as trance-inducing techniques that use bodily rhythms as medium. Dancing and swaying are the two natural ways of expressing rhythm with the body. The trance walking and hyperventilation as two special kinds of trance working are belonging to this category, too.
It is well-known that dancing is one of the best ways of getting into trance. Everyone who is used to visit discos is familiar with this effect. Traditionally the Sufis use a kind of whirling dance to induce trance very quick. In spite of whirling the whole body the shaking of the head produces similar effects (hi there, headbangers!). The various voodoo-cults throughout the world use the rhythmic dance, too. Music is frequently being used as the vital part of inducing trance (see below), besides the dance. The photography shows voodoosi in Benin which dance the bird-dance and are fully in trance during the dance.
The dancers are already in deep trance when they start to dance the bird-dance - the music already has done its job. They know the rites and the music deep in the bones from their earliest childhood. The "Certainty" or belief and the experience are deeply anchored and trance and possession can take place much easier. The more you can identify yourself with the things happening the easier it is to get into trance. Some people with "rhythm in the blood" can fell much easier in trance then others. Some others are in such deep states of trance that it is difficult to come down for them again.
Shaking and Swaying is another kind of inducing trance (or a sign of deep trance). Jan Fries called this "Seiðr", a term used in old nordic resources, translated as "seething" or "cooking". Seething is the best term to describe the ecstatic sensations and experiences you have during seiðr Practitioners were called "Seiðmadr", "Seiðberandi", "Seiðman" or the female form "Seiðkona". During the early middle-ages these art already was nearly extincted here in Germany. The trance expresses itself with shuddering, swaying or intense shaking of the body. The bushmen from the Kalahari desert, the San and the !Kung, induce the trance first by dancing and hyperventilation. After the trance kicked in, they begin to shake and sway. They call this state "KIA" — a term Spare used for describing the atmospheric ego. Within KIA the thoughts come to an end and Spares "Neither-Neither" is being reached. The ego is dead and KIA acts freely. The frequency of the shaking also determines the trance-experience: slow swaying induces different states then fast shaking or shuddering.
In the himalayan regions there were some lamas who used to run over long distances without getting tired. The rhythm of walking or running can induce a trance-state, too. After a certain time of running - which varies much - a rhythm takes control of the walker and is no longer subject to fatigue. The distances covered can be tremendous. The 100 km walks or the extreme marathons are an example. Very important is the goal of your walk. It is not possible to run further after you reached the mark you wanted to reach. I myself used the stars as a fixation-point during my own walks ...
Another method of inducing Trance is hyperventilation. On one side this technique uses a fast rhythm of breathing, but the trigger of the trance is much more the hypocapnia you get because of a reduced pCO2 in your blood. Signs of it are: paraesthesia of extremities (tickling) and the mouth, headache, pawlike hand-position and generalized cramps (hyperventilationic tetania). Hyperventilation in combination with Seið or Dance improves the trance. During trance the ventilation patterns changes again, but is still keeping the state up for a time. It is a secure way of inducing trance - except if you are hysteric or otherwise mentally ill.
The rhythmic drumming is a sound heard in most drumming circles of modern shamanism. Often the trance-inducing power of the drum is being explained by the influence, certain beating frequencies have on the brain-wave patterns of the listener. A rhythm of 4 to 5 bps is said to be necessary. Also if someone works at a machine or near rhythmic sounds, produced by machines, the person is easily falling in a trance-like state, too. Most of the time these people are in a trance, but with a strong relation to the activities they are doing. Bodily, optical and acoustical stimulation are playing together then. Within the voodoo culture more complicated and faster rhythms are preferred for trance induction. The drum is not the great trance-inducing instrument for shamans, as always is being stated loudly. Very often other instruments are used like rattles, sticks, bows, singing bowls, didjeridoos or the voice. Siberian shamans are already in deep trance, before even reaching for their drums. Often they are in a seið-like trance. Nearly any rhythmic sound produced by literally anything can be used to entrance the audience. It is not clear, why mankind reacts with altered states of consciousness while listening to rhythms. The physiologic explanation with α, β and θ waves and the influence of the rhythms of these is a shaky construct and not at all the last theory to be formulated. An interesting note, by the way: During the first nine months of life inside the womb of our mother we all have heard a steady rhythm just nearby: the beating of her heart. Perhaps the key to our trance-states is hidden there.
Leading over to the optical stimulations I mention the guided meditation and hypnose as acoustic ways of inducing trance. With modulated speaking the listener can easily be led into various levels of trance. Within most techniques of hypnose suggestive speaking is a vital part. Another form of rhythmic induction is Mesmers magnetism - which I consider a mixed form of sensoric, optic, suggestive and other influences.
Optical Induction of Trance
Rhythmical movements, being watched, can induce trance as easy as the other described methods. The swinging pendulum in hypnotic therapy is well-known as an example. Rhythmic dances and dancers, sun-rays reflected from a body of water, waves on the high-sea, rhythmic flashes (dream-machine!) are all belonging to the optical induction method. Siberian shamanism use the head-gear for additional trance-induction. Leathery fringes hang in front of the eyes of the shaman and move with each movement of the shaman. The shaman can see better with these.