Entrainment/Frequency Following Response

The entrainment/frequency following response is the tendency for our mind and body to be effected by and synchronize to an external source -- such as a particular sound or rhythm. This has important implications in the design and use of psychoacoustic music.

Christian Huygens, a Dutch scientist of the late 1600’s, observed an interesting phenomenon concerning pendulum clocks that were mounted on the same wall. He would start the motion of each clock’s pendulum at different angles and rates of speed. Very quickly, each clock began to change the swing of its pendulum until they all swung together, perfectly synchronized, at the same angle and rate of speed. If he moved one of the clocks to an opposite wall, this synchronicity did not occur between the recently moved clock and the clocks still moving together on the other wall. The vibrations on the shared wall created the means by which each clock "communicated" with the other, and thus they entrained themselves to the same beat pattern of movement.

Studies (Atwater, 1997; Rosenfeld, Reinhart, and Srivastava, 1997) have shown that we also experience this "entrainment" process. People, like the pendulum clock, have various rhythms (another way to look at vibration and bodily oscillatory movements, such as heart rhythms or brainwave patterns) that are continually in motion. By presenting our bodies with an appropriate external rhythm that vibrates our tissues or auditory system, we experience the same entrainment process as the Huygens’ clocks. (Hink, 1980)

Binaural Beats and "Binauralized" Instruments

We are bilateral beings, both hemispherically and physiologically. This has important implications concerning the way in which we perceive sound. For example, when a person listens to two slightly different musical tones at the same time, one tone in the left ear, and a different tone in the right ear, a third "resonant" beat is experienced (heard) by the listener. This third resonant sound is neither of the two original sounds but instead is the experience of our brain attempting to interpret and synthesis the original two tones together (Oster 1973). This sets up an internal resonance that alters our current perceptual state and brings about a synchronous "cross-talk" between the left and right hemispheres of the brain (Foster 1990; Sadigh 1990).

Beyond the Drone of Binaural Beats

Most binaural beat recordings that you hear utilize a simple sine wave to create the neurological binaural beat response. While effective in this regard, it can also be extremely monotonous in nature and sound like a low level "drone" in the background of the musical composition. While this is useful for various applications, such as meditative practices or in sleep CDs, such as a backdrop to the third track of Sound Sleep, it does not include the contextual component of healing music. This facet defines the nature and feel of the music. In order to take advantage of this neurological response as well as make it pleasing in a musical composition, I have created various electronic instruments that produce both pleasing, complex sounds as well as create the binaural beat response. These instruments are used all throughout my recordings and CDs.

Natural Sounds

Have you ever fallen asleep on the beach listening to the rhythmic tides of the sea as they wash back and forth from the shore?

Have you ever been in an airplane and was lulled by the airy noise and drone of the engines (especially the Canadair CL-65, my favorite plane noise :)?

Have you ever found comfort by laying your head on a loved one's chest and drifting off to the rhythm of their heartbeat?

These are all examples of the powerful impact natural sound can have on your mind and body. This knowledge is used as a foundation to the type of psychoacoustic sounds that you will find in the recordings at The Heart Of Sound. These sounds play an important role in activating our relaxation response. The effects of these types of sounds are deeply imbedded in our physiology via the parasympathetic and sympathetic aspects of our autonomic nervous system. They are part of our unconscious mind via association and conditioning. The latter began in the womb as our first memories were molded in the warm, watery embrace of amniotic fluids. It was there that we grew, listening to our mother's heartbeats, hearing the gurgling, deep rumblings of her digestive system and the rhythmic flow of air as her lungs expanded and contracted.

By immersing ourselves in the sounds of these embryonic beginnings, we can reconnect with a state within ourselves when we were most secure, protected and at ease. Once emerging from the womb, we discover other sonic soundscapes that bring us back to the relaxed state of that formative beginning – the soft stir and rustling of wind through the trees, the rhythmic sounds of the tides and even the whooshing drone inside of an airplane.

Nonlinear Patterns and Ambient Music

In the high beta waking state, our minds tend to structure and organize information, constantly analyzing and categorizing experiences. This effort takes a great amount of attention and energy. While this is useful in many contexts, this mental posture is not the most effective state for deep systemic relaxation and regenerative mind/body processes (such as are experienced in deep, healthy sleep) or for meditation practices (such as zazen or insight/Vipassana meditation).

In order to encourage those types of states (relaxation and/or meditational) acoustically, music must have a structure and flow that is non-predictive in nature, such as the second track of Deep Waters. It must have a non-linear orientation so that your mind has nothing to hold onto -- nothing that it can predict or expect. When your mind is presented with non-linearity, two things happen. One, the faculties that unconsciously anticipate and ask the question "What's coming next?" are eventually short-circuited. Then, two, another facet of mind arises -- one which is imagery rich and free flowing in nature. It is at this point that your conscious and unconscious minds meet in that inbetween playground of imagination and inspiration. This is a state where healing and regeneration can begin on multiple levels since the high-amplitude beta conscious mind has been taken "offline".

Rhythmic Pulses

Acoustic pulses in sound and music (which we understand as rhythm) have powerful entrainment qualities. Most people have a resting heart rate between 60-100 beats per minute. This can drop as low as 40 beats per minute during sleep. Another powerful physiological rhythm is the slow undulations of the meningeal sheath as cerebral spinal fluid flows up and down the spine. These rhythms pulse between 5-12 cycles per minute. Many of the recordings at The Heart of Sound have variable rate rhythms that begin at a higher rate and eventually slow down to slower rhythms, coaxing the body to sympathetically respond with correspondingly slower physiological rhythms.