Rhythm and entrainment
Episode 7 in a series of 12 articles based on my sound therapy training final paper, written in 2012. The influence of sound, rhythm and rhythmic entrainment on our personal state and development.
As mentioned, our body and psyche is sensitive for external rhythmic patterns that can attach themselves to our way of being and influence our behaviour.
Entrainment is integral to any musical effect. It affects our way of being (internal) through external tempos, and is also the method by which our body pulses synchronize with each other. Given that rhythm is found everywhere, entrainment is an important influence to our life experience.
The recognition of patterns in sound or activity is one of the ways a brain conserves energy. Whenever we experience a vibration within any of these brainwave states our brain will be entrained into the same frequency – normally in less than a minute. In science this is referred to as “the frequency-following response.” Just about all rhythms fall into the brainwave range. Therefore, almost every rhythm in the music we listen to entrains our brain. Our brains are commonly entrained by the rhythms around us.
When it comes to rhythmic entrainment, there are two paths to consider with habituation. If you want habituation to take place than a rhythm needs to be nice and steady. It works well in less active brain states like alpha, theta and delta. Doing the opposite will keep the listener in active beta state by for instance subtle changes in ongoing tempos and will avoid habituation.
The brain is sensitive for non-periodic rhythms while entrainment is based on periodicity. Therefore the changes in rhythm need to be very subtle and just enough to keep the auditory system alert. This is a fine line between disturbance and entrainment.
As in nature, the natural rhythmic pulse is not based on metronomic or mechanic precision; for a rhythm to sound natural and ‘soulful’ it needs to have a groove. A slight alteration in tempo that generates a natural feel instead of sounding mechanic. As in music, rhythm is organized sound, but the organization has to involve some element of the unexpected to remain natural.
Rhythms from nature include waterfalls, river flowing over stones and bubbling, sea waves, wind of trees. The cycle of these nature rhythms will have a calming effect on most of us. A charging effect will be achieved by listening to higher pitched sounds and rhythm of frogs, crickets and cicades and bird sounds. Nature sounds and their resonance can be used to instil a creative, entrainment or psychological impact.
Besides entrainment through sounds, we can get the same effect with flashing lights. When driving on a road shaded by series of trees, the sun light will hit your eyes with a certain rhythmic pattern that can generate a brain wave state.
The cerebellum, located at the lower back of your head, is the part of the brain that is closely involved with timing and coordinating movements of the body. Evolutionary, the cerebellum is one of the oldest parts of the brain and although relatively small, it contains 50 to 80 percent of the total neurons. The main function for this part of the brain is timing.
In all animals that have brains, the cerebellum is involved in maintaining gait, the pace at which certain repetitive movements are made. The cerebellum also makes a distinction between noise and rhythm; when exposed to receiving noise it is not activated, while it does track the beat when listening to rhythmic music.