Glossary & References


Brainwave Entrainment 

Brainwave Entrainment refers to the brain's electrical response to rhythmic sensory stimulation, such as pulses of sound or light. When the brain is given a stimulus, through the ears, eyes or other senses, it emits an electrical charge in response, called a Cortical Evoked Response (shown below). These electrical responses travel throughout the brain to become what you "see and hear." This activity can be measured using sensitive electrodes attached to the scalp.

Brain Entrainment Diagram 2

When the brain is presented with a rhythmic stimulus, such as a drum beat for example, the rhythm is reproduced in the brain in the form of these electrical impulses. If the rhythm becomes fast and consistent enough, it can start to resemble the natural internal rhythms of the brain, called brainwaves. When this happens, the brain responds by synchronising its own electric cycles to the same rhythm. This is commonly called the Frequency Following Response (or FFR)

Brain Entrainment Diagram

FFR can be useful because brainwaves are very much related to mental state. For example, a 4 Hz brainwave is associated with sleep, so a 4 Hz sound pattern would help reproduce the sleep state in your brain. The same concept can be applied to many other mental states, including concentration, relaxation and meditation.6 7 8 If you listen closely during an NP3 session, you will hear small, rapid pulses of sound. As the session progresses, the frequency rate of these pulses is changed slowly, thereby changing your brainwave patterns and guiding your mind to various useful mental states.

What is Entrainment?

Entrainment is a principle of physics. It is defined as the synchronisation of two or more rhythmic cycles. The principles of entrainment appear in chemistry, neurology, biology, pharmacology, medicine, astronomy and more.

CASE IN POINT: While working on the design of the pendulum clock in 1656, Dutch scientist Christian Huygens found that if he placed two unsynchronised clocks side by side on a wall, they would slowly synchronise to each other. In fact, the synchronisation was so precise not even mechanical intervention could calibrate them more accurately.



Classical Conditioning

Also known as Pavlovian or respondent conditioning, refers to a learning procedure in which a biologically potent stimulus (e.g acupuncture) is paired with a previously neutral stimulus (e.g music.) It also refers to the learning process that results from this pairing, through which the neutral stimulus comes to elicit a response (e.g., well being) that is usually similar to the one elicited by the potent stimulus. These basic facts, which require many qualifications, were first studied in detail by Ivan Pavlov through experiments with dogs. Together with operant conditioning, classical conditioning became the foundation of behaviorism, a school of psychology which was dominant in the mid-20th century and is still an important influence on the practice of psychological therapy and the study of animal behaviour today. Classical conditioning is now the best understood of the basic learning processes.




Also known as brain plasticity or neural plasticity, is an umbrella term that describes lasting change to the brain throughout an individual's life course. The term gained prominence in the latter half of the 20th century, when new research showed that many aspects of the brain can be altered (or are "plastic") even into adulthood. This notion is in contrast with the previous scientific consensus that the brain develops during a critical period in early childhood and then remains relatively unchanged (or "static"). Neuroplasticity can be observed at multiple scales, from microscopic changes in individual neurons to larger-scale changes such as cortical remapping in response to injury. However, cortical remapping is more extensive early in development. Behaviour, environmental stimuli, thought, and emotions may also cause neuroplastic change through activity-dependent plasticity, which has significant implications for healthy development, learning, memory, and recovery from brain damage. At the single cell level, synaptic plasticity refers to changes in the connections between neurones, whereas non-synaptic plasticity refers to changes in their intrinsic excitability.




Is the scientific study of sound perception. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound (including speech and music). It can be further categorised as a branch of psychophysics. Psychoacoustics received its name from a field within psychology—i.e., recognition science—which deals with all kinds of human perceptions. It is an interdisciplinary field of many areas, including psychology, acoustics, electronic engineering, physics, biology, physiology, and computer science.




Sometimes Quadrophonic or Quadrasonic sound — similar to what is now called 4.0 surround sound — uses four channels in which speakers are positioned at the four corners of the listening space, reproducing signals that are (wholly or in part) independent of one another.