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Introduction to Beat Waves

Physics is applicable everywhere. Every action that we undergo will definitely have an idea of Physics behind it. We were aware of the concept of sound and its various formats such as in the form of noise, melodious such as the sound of any musical instrument, etc. Using the concept of beats many musical instruments have been developed. Even a minute change in beat can result in an extraordinary tune. Beat waves are not only used in the music industry but also in the medical field. These days, in order to treat many neural disorders, doctors use beat wave therapies.


To produce a melodious tune or song, the musician needs their instrument to have the correct sound. They produce the desired frequency by adjusting the equipment and try to match it with their instrument’s frequency. If the two frequencies are not matching, they will interfere to produce alternating loud and soft sounds. 


A sound wave not only propagates in space but also can propagate through time. Thus, if the two sound waves can produce interference by overlapping in space, they should also be capable of producing an interference pattern when they overlap in time. This phenomenon is called beats and the waves are known as the beat waves.


Gamma Binaural Beats

Beats occur when two waves of nearby frequencies overlap and create a new resultant wave. Using the same idea of producing beat waves not only music but can also be utilised in the field of medicine for curing many neural disorders. One among such treatments is gamma binaural beats therapy. Even before we start with gamma binaural beats therapy, let us understand what we mean by binaural beats.


Basically, the binaural beats are of the two different types of beat waves with different frequencies that are heard separately, one in each ear. Our brain is capable of processing the difference between these two beats to understand the difference between the frequencies. Binaural beats are certainly dangerous as they can cause noise-induced hearing loss which will ultimately result in permanent loss of hearing over a period of time. Binaural beats in sound waves is an auditory phenomenon in which the eardrum ruptures or the middle bone in the ear can get damaged.


Now, binaural beat therapy is an emerging form of sound wave therapy that is found to be having a high success rate. Binaural beats waves therapy utilizes the fact that the right and left human ear each receive a slightly different frequency tone, yet the brain perceives and processes these dissimilar frequencies as a single tone. Binaural therapy is currently being recommended for the treatment of anxiety, stress, and related disorders that are found to occur mostly in all age groups. Binaural therapy is actually a self-help treatment and it is usually available in the form of audio recordings that a person listens to on stereo headphones.


Now, the gamma binaural beat therapy, as the name itself suggests here we will be using gamma waves to treat neural disorders. This is also known as the gamma pattern in medical terms and gamma binaural beat therapy, the frequency pattern accounts for a range of 30–50 Hz. The study of many doctors and scientists suggest that these frequencies promote the maintenance of arousal while a person is awake.


As the leading authorities in psychiatric treatment have no recommendations for binaural beats, it is usually the producer of the tape that makes the suggestions for use. People should follow the instructions carefully before they start with gamma binaural beat therapy, delta binaural beats (or binaural beats delta waves) or beta binaural beats therapy. Those who do not find any difference or do not notice any reduction in anxiety might benefit from trying a different producer, type of sound, or frequency. It is most important to avoid using gamma binaural beats therapy or any other binaural therapies while undertaking tasks that require alertness and full attention.


Beats in Sound Waves:

Now, how do the beats in sound waves are produced? Let us understand with an example, consider two beat waves with two different frequencies f\[_{1}\](say purple) and f\[_{2}\](say green). The waves are interfering constructively in the green highlighted regions, leading to a larger amplitude when the waves combine in f\[_{B}\]. The white highlighted regions are where destructive interference occurs, and the amplitude of f\[_{B}\], is smaller than the original sound waves. The variation in amplitude results in the alternating volume or the loudness of sound that we call beats or beat waves.

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Let us consider another example, for understanding how beats in sound waves are produced. We will need two tuning forks (turning fork) of close frequencies e.g. 800Hz and 850Hz. Both the frequencies are almost identical and there is no major or intense difference in the audible frequency. You hear when you play each of them individually, but when played together these two frequencies, they will overlap with each other, as they are very close to each other in terms of frequencies and their crest to crest interference produces a constructive interference and which in turn results in the increase of the amplitude of the wave hence the loudness of sound increases, resulting in the production of beat waves. 


When a crest to trough meet the resulting interference will be destructive in nature, hence they both will end up cancelling out each other and thus the amplitude produced will be equal to zero. Hence the loudness will suddenly drop to zero or reduce to zero. The frequency at which the intensity of the loudness increases and decreases is known as the beat frequency. This beat frequency is always equal to the difference between the two frequencies which produced it. This is how the beats in sound waves are formed.


Did You Know?

  • We know that all matter is made of small particles known as molecules. When a sound wave is generated, the molecules end up bumping into one another in a particular pattern. Those molecules bump onto the next set of molecules, which in turn bump into the next molecules and so on. This collision continues until the energy runs out. The best example can be,  have you ever thrown a rock into a pond, then we will notice the rings of water waves that move out from the place where the rock landed. This is much the similar way that sound waves travel.

  • One of the most important things to remember about the wave motion of the particles or the waves is that they transport energy, not matter. This criterion makes them different from another phenomenon in physics. 

  • The finest and tallest ocean wave ever witnessed and recorded was 1,720 feet tall and occurred in Lituya Bay in Alaska.

  • The Doppler Effect is experienced when the sound waves from the moving object are moving toward the observer, i.e., under the relative motion. As the object moves closer to the observer, the distance between the object and the observer gets shorter. Because of this decreasing distance, the sound waves are being compressed between the two, i.e., between the object and the observer. As the object moves further away from the observer, the distance increases and it takes longer for the sound to reach them. The sound then appears to be lowered. The actual frequency of the sound wave never actually varies.

FAQs (Frequently Asked Questions)

1. How Do Sound Waves Produce Beat?

Ans: The production of the beat in sound waves will occur, when a crest to trough meet the resulting interference will be destructive in nature. Hence they both will end up cancelling out each other and thus the amplitude produced will be equal to zero. Hence the loudness will suddenly drop to zero or reduce to zero, the frequency at which the intensity of the loudness increases and decreases is known as the beat frequency. This beat frequency is always equal to the difference between the two frequencies which produced it. This is how the beats in sound waves are formed.

2. What is a Beat in Sound Waves?

Ans: Beats are just the result of interference of the two different frequencies.

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