| Psychoacoustic is the study of perception of sounds. | | | | between 1 and 30 Hz in order for the effect to take |
| It basically focuses on how we listen and the | | | | place. For example, if a pure tone of 500 Hz is |
| physiological effect of music and sound on the | | | | presented to the right ear and a pure tone of 510 Hz |
| nervous system. | | | | is presented simultaneously to the left ear, a |
| Human auditory perception | | | | “binaural beat” of 10 Hz, the difference |
| The typical human hearing range is between 20 Hz | | | | between the two tones, is experienced. The |
| and 20,000 Hz. Software and the psychoacoustic | | | | brain’s ability to detect a waveform phase is |
| models are based on the ear’s limitation in | | | | what enables it to perceive binaural beats. |
| perceiving sounds. They provide lossy compression, | | | | Effects of Listening to Binaural Beats |
| which determines which frequencies can be removed | | | | Binaural beats may influence functions of the brain. |
| without significantly affecting the perceived sound | | | | Since they are perceived as auditory beats, they can |
| quality. | | | | theoretically be used to entrain specific neural |
| Masking effects | | | | rhythms through frequency-following response (FFR). |
| One of the main elements of psychoacoustics is the | | | | This is when brain waves tend to entrain to or |
| masking of spectral sound elements in an audio signal | | | | resonate at the frequency of an external stimulus. |
| like tones and noise. This is done by the use of | | | | Therefore, it is theoretically possible to utilize a |
| special encoding programs that “mask” | | | | specific binaural-beat frequency as a consciousness |
| frequencies that is beyond or below the human | | | | management technique to entrain a specific |
| hearing range. Masking is when a softer sound is | | | | brainwave activity. |
| covered by the presence of the louder sound. For | | | | Binaural beats are usually used to induce various |
| example, in an audio signal a masking threshold is | | | | states of consciousness. Depending on the frequency |
| calculated. If a certain tone is below the masking | | | | of binaural beat stimulation, the effect on someone |
| threshold it will be masked by the louder tone. | | | | may be stimulating or relaxing. Binaural beats |
| Binaural beats | | | | frequencies that range between 1 to 4 Hz (Delta) |
| Binaural beats were discovered in 1839 by a German | | | | and 4 to 8 Hz (Theta) have been associated with |
| experimenter, Heinrich Wilhelm Dove. However it was | | | | relaxed, creative, sleepy and meditative states. Alpha |
| Gerald Oster’s article “Auditory beats in the | | | | frequencies (8 to 12 Hz) have increased brain wave |
| Brain” published in 1973 that brought new insight | | | | activity, which could correspond to a relaxed while |
| on the research of Binaural Beats. | | | | awake state. Beta frequencies (16 to 24 Hz) have |
| Binaural beats or binaural tones are auditory | | | | been associated with active, busy, arousal, stress and |
| responses, the perception of which arises in the | | | | alertness. |
| superior olivary nucleus of the brainstem. They result | | | | |
| from the interaction of two different frequencies, | | | | Research and interest on the neurological component |
| originating in opposite ears simultaneously using | | | | of sound in the field of psychoacoustics have rapidly |
| headphones. The frequencies must be below 1000 Hz | | | | grown in the past few decades. Binaural Beating is |
| in order to “hear” the beats. The two | | | | being used in a variety of fields like music, therapy, |
| opposing frequencies must have a difference | | | | neurosciences and education. |