Human Hearing Threshold & Binaural Beats

The science behind binaural beats occurs naturally in the brain. A different sound (tone) frequency is sent to the left and right ears through headphones.

Upon hearing the two different frequencies, the brain interprets one consistent, rhythmic frequency, known as a binaural beat(s).

The resulting frequency, interpreted by the brain, is the mathematical difference between the two frequencies sent to the left and right ears.

The brain then follows along at this frequency and produces brainwaves of the same frequency.

This theory is known as ‘Frequency Following Response' (FFR); a naturally occurring science that happens in the human brain.

Entraining the brain through sound isn't just a modern trend. It is something that has been part of human societies for centuries.

In this article, we'll step back in time and look at some primitive forms of brainwave entrainment and music therapy. We will also learn how binaural beats were discovered, how they work, and the scientific evidence for their effectiveness.

The word binaural means “having or relating to two ears”. This represents the process, which works by simultaneously sending a different sound frequency to each ear through headphones.

The entrainment happens inside the brain and is caused by a physiological response.

Upon hearing two tones of different frequencies – sent simultaneously to the left and right ears – the brain perceives a new tone, or third tone, as some refer to it, based on the mathematical difference between the two frequencies.

The brain then follows along at the new frequency and produces brainwaves at the same rate of Hertz (Hz), thus becoming “entrained” to that frequency.

Hertz (Hz) is the way we measure a cycle of sound. 1 Hertz means one vibration cycle per second

For example: If a 200 Hz sound frequency is sent to the left ear, and a 205 Hz frequency to the right ear, the brain will perceive a new frequency at 5 Hz –  the difference between the two.

The brain then follows along at the new frequency (5 Hz), producing brainwaves at the same rate of Hertz (Hz). The technical term for this process is ‘Frequency Following Response'.

The brain will only respond in the intended way if it receives the sound frequencies at the same time through headphones. You can test this for yourself using the test tone further down the page.

All you have to do is put on a pair on headphones, relax and press play. It's that easy.

As explained above, we can listen to binaural beats to encourage the brain to produce brainwaves of a specific type (state). There are five main brainwave states, as follows:

1. Delta: 1-4 Hz
2. Theta: 4-8 Hz
3. Alpha: 8-14 Hz
4. Beta: 14-30 Hz
5. Gamma: 30-100 Hz

The states ascend in terms of speed, starting at the slowest frequency waves, delta, to the fastest frequency waves, gamma.

The effect listening to binaural beats has on your brain is dependent on the frequency of the track and the brainwaves it stimulates production of.

For example: To induce deep relaxation, we can listen to Theta wave music.

And to encourage deeper sleep , we can listen to Delta wave music.

The graphic below shows the five main brainwave state categories used in binaural beats music, and their associated benefits:

The benefits listed under each brainwave state are general associations. It should not be assumed that all frequencies within a state’s range will produce all the listed benefits.

There are specific frequencies associated with specific states of mind, and indeed different results can be experienced in the high, middle, and low areas of each brainwave state.

Although the creation of binaural beats music has only been possible through technological advancement in the last 100 or so years, the use of this type of sound therapy dates back thousands of years.

Ancient cultures were aware of how the brain could be entrained through sound repetition long before modern science was able to prove the process.

History notes many examples of music used as medicine and therapy:

1. The ancient Greeks used music to ease stress, promote sleep, and soothe pain.
2. The Native Americans and Africans used singing and chanting as part of their healing rituals.
3. Even in language we see a connection between healing and music. For example, the Chinese character for medicine includes the character for music.

Of course, in times past, societies didn't refer to music therapy, binaural beats, or brainwave entrainment of any kind. 

But what they did know was that sound had powerful healing properties.

Indeed, in almost every ancient culture, repetitive beat formats have played an important role in well-being and prosperity. of ancient cultures and found that they generally beat at a steady rate of 4.5 beats per second.

This consistent beat induced a trance-like state for the tribe, due to the brain following along at a 4.5 beats-per-second brainwave frequency, which is a low Theta brainwave state, as you'll learn about later on.

Lenzy noted:

The pattern of the drumbeat as it relates to beats per second can be correlated with resulting temporary changes in brain wave frequency (cycles per second) and/or subjective experience, provided the drumming pattern is sustained for at least 13 – 15 minutes.

This research supports the theories that suggest that the use of the drum by indigenous cultures in ritual and ceremony has specific neurophysiological effects and the ability to elicit temporary changes in brain wave activity, and thereby facilitates imagery and possible entry into an ASC (altered state of consciousness).

Indeed, in almost every ancient culture, repetitive beat formats have played an important role in wellbeing and prosperity.

For example: through the use of repetitive drumming and chanting, Yoruba, Ifa Priests, Tibetan monks, First American shamans, Hindu healers, and master Yogis have been able to induce specific states of being for meditation, transcending consciousness, and healing.

TruceTalk® Binaural Hypnosis beats provide benefits in the same way, helping with deeper meditation, stress release, reduced anxiety, improved focus, better sleep, and more.

The way in which binaural beats work was first discovered in 1839, by a Prussian physicist and meteorologist named Heinrich Wilhelm Dove.

Dove was a keen experimenter, and it was one of his experiments that would pave the way for exploration in the field of brainwave entrainment.

Of course, headphones weren’t available back then, so Dove conducted the following experiment to make his discovery:

Dove had his subject stand in a room. Then, on one side of the room he placed a tuning fork. The fork was connected to a tube that ran to the subject's ear.

Dove then placed a tuning fork on the other side of the room and ran a tube to the other ear.

The forks didn't vibrate at quite the same low frequency, so the subject received different frequencies to the right and left ears.

Dove documented that his subject perceived the effect of the two frequencies combining as a slow beat. We now know this to be the same theory behind the binaural beats phenomena.

Dove made the discovery but didn't connect all the dots.

Indeed, it wasn't until 1973 that biophysicist Doctor Gerald Oster brought binaural beats into mainstream awareness in a paper called ‘Auditory Beats in the Brain' (Scientific American, 1973).

Oster's paper tied-together the different aspects of research that had taken place since Dove's discovery. He gave the subject renewed relevance to modern scientific questions regarding how sound might aid impairments.

Oster viewed binaural beats as having both research value, and as a potential diagnostic medical tool.

In terms of research, he saw the potential for binaural beats to explain features of the auditory system; not least how we locate sounds spatially in our environment and selectively single-out individual sounds from background noise.

From a medical perspective, Oster saw potential to not only diagnose auditory impairments, but to identify a range of seemingly unrelated medical issues.

For example: Oster found strong data that suggested diminished ability to hear binaural beats was an early predictor for Parkinson's Disease.

He also found that variation in the ability to perceive binaural beats correlated subtly with when female subjects were in hormonal cycles.

But central to his thesis, and indeed what sparked renewed interest and research into how binaural beats might help with modern day afflictions such as anxiety, insomnia, pain issues, and memory problems, was that binaural beats involve different neural pathways than conventional hearing, and that listening evokes specific neural responses.

Forty nine years on, and lots of research by scientists and music researchers later, binaural beats (brainwave entrainment) music is used by people all over the world to assist in stress and anxiety relief, help with concentration and memory issues, improve sleep, and provide pain relief,