An Ultimate Guide on the Uses of Beats

Beats are alternate loud and soft sounds. When two different sound frequencies interfere with each other, their difference sounds as beats. They are a result of the superposition of waves. Both sound waves involved have slightly different frequencies. When such waves overlap with each other, we obtain constructive and destructive parts in the resultant wave. Thus, their superposition causes the intensity of the resultant sound to vary periodically with time. Such variation can be controlled and placed properly to create music. Beats also help determine the difference in frequencies. The value of beat frequency can never be negative.

How are Beats Produced?

Beats are produced by the regular waxing and waning of two interfering waves of sound travelling in the same direction. During the interference of such waves, when two peaks overlap, they produce a constructive wave. When a peak and a valley of the wave meet, they produce a destructive wave. This is known as waxing and waning. This phenomenon physically results in occasional loudness and softness of sound, resulting in beats.

Application of Beats

A few common applications of beats are presented below.

• Tuning musical instruments

This is quite a common application of beats. The stringed instruments are adjusted as per the standard frequency for getting a pleasant sound. The musicians play the standard sound and simultaneously play the stringed instrument. While doing so, if there is a difference in frequency, beats can be heard distinctively. They aim to reduce the beats and make the instrument’s sound similar to the standard sound. It is also used in multiphonics, where beat frequencies are purposely used to develop a musical effect.

• Doppler RADAR

The speed of an aeroplane can be determined using a Doppler RADAR. It is based on the beats phenomenon. A source with a known frequency is used. The frequency is received after the reflection from the aeroplane is recorded. Both the frequencies have differences that give rise to beats. With the help of these beats, we can calculate the speed required. Similarly, a car moving faster than the minimum speed on the road can also be detected using the same effect. In the medical field, echocardiograms and Doppler ultrasonography also depend on the beats phenomenon.

• Finding unknown frequency

Two frequencies are played simultaneously, one of which is unknown. Based on the value of the beats, we can get the difference between the two frequencies. Suppose we received the beat frequency as 3Hz, so the unknown frequency will either be 3 Hz greater or lesser than the known frequency. For determining this, we will adjust the known frequency to such an extent that we will not get any beats. By doing this, we are equating the known frequency to the value of the unknown frequency. Thus, we can obtain the frequency of the unknown source.

• Detection of harmful gases

The phenomenon of beats is helpful in detecting dangerous gases in mines. We know that sounds require a medium to travel from, and that medium is the air on earth. When the air inside a mine is polluted, it will naturally have greater potential to let sound waves travel with greater velocity. This results in higher frequency, which creates a difference from the source frequency and produces beats. This becomes an alarm, thereby warning people before entering the mines.

• Binaural beats

Binaural beats use the beats phenomenon to create an illusion where the brain hears a third frequency that is a different frequency from what is played. In aligning two different frequencies, our brain tends to interpret it as a difference in both frequencies. Our brain tends to align its activities as per the frequency heard. This is known as the frequency-following effect. Different binaural beats help attain different mental states like reducing stress, sleeping, focusing, increasing creativity and learning capabilities, etc. 

Uses of Beats in Physics

Sonometer experiment

The sonometer experiment is the perfect example of the one of the uses of beats in physics. When two waves superimpose, they cause interference of frequencies. The beat frequency is the result of this phenomenon. In a sonometer, a piece of paper is balanced on the string of the device. At a particular length, the tuning fork’s frequency brought near to the string produces similar vibrations in the string, causing the paper to fall. Based on the beats phenomenon, the fundamental frequency of the string can be determined. The three laws of the vibrating string can, thus, be verified. 

Conclusion

The beats frequency phenomenon has a wide range of applications in physics as well as in medical science. Remember that the waxing and waning of waves are also the constructive and destructive interference of waves. We physically hear the beats in the form of consecutive louder and softer intensities of sound. The applications of beats are becoming increasingly common. Nowadays, highways and flyovers have devices attached that automatically capture the speed of the vehicle passing. If the vehicle crosses the minimum limit on that road, it quickly takes a picture of the vehicle number, and later, the police take the necessary actions. This is also based on the beat frequency phenomenon. The beat frequency phenomenon also has its application among radio signals and broadcasting networks.