Sound

Sound plays an important role in our lives. It is very useful for communication. It highlights the significance of sound in interpersonal communication. In addition, the chapter explains how sound is produced. Students will also learn how sound travels from one location to another. This chapter will also provide an answer to the question of how we perceive sound. Furthermore, this section will address the issue of some sounds being louder than others.

The origins of sound are explained in this chapter. It then discusses how humans produce sound. Aside from that, this chapter will teach students about the mediums required for sound propagation. The chapter also discusses vibration amplitude, time period, and frequency.

Sound and Vibration:

The backward and forward movement of a body is known as vibration. Sound is produced by vibrating objects such as musical instruments like Guitar.

Propagation of Sound:

• Sound travels through a medium (gas, liquid or solid) and is carried in all directions.
• The sound cannot travel through a vacuum.
• In humans, the sound is created by the voice box or the larynx. 
• It is at the upper finish of the windpipe.
• Two vocal strings are extended across the larynx so that it leaves a thin cut between them for the section of air. 
• At the point when the lungs power air through the cut, the vocal lines vibrate and produce sound. 
• Muscles joined to vocal strings can make the lines tight or free to deliver various voices.

Sound Produced by Humans:

Hearing as a process:

The ear is the organ for hearing. The outer area of the ear looks like a funnel. At the point when sound enters it, it goes down a trench towards the end of which there is a stretched membrane. It is called the eardrum. 

• The eardrum is like a stretched rubber sheet. It senses the vibrations of sound and starts vibrating.
• The eardrum sends vibrations to the inner ear. Then the signal goes to the brain and the process of hearing completes.

The forward and backward movement of a body is called vibration. This movement is also known as oscillatory motion.

Amplitude: It can be defined as the loudness or the amount of maximum displacement of vibrating  particles of the medium from their mean position when the sound is produced.

•    Greater the amplitude of vibration, the more  the sound.
• Smaller the amplitude of vibration, the feeble is the sound.

Time Period: It is the time taken to complete one oscillation.

Frequency: Total number of waves produced in one second is called the frequency of oscillation. Frequency is expressed in Hertz. Its symbol is Hz. 

The frequency decides the harshness or pitch of a sound. 

With high frequency, the pitch is higher and the sound is louder.

Bring down the frequency of vibration, the lower is the pitch. 

A bird makes a shrill sound while a lion makes a low-pitched thunder. Be that as it may, the thunder of a lion is exceptionally uproarious while the bird is very weak. 

The frequency of the voice of a youngster is higher than that of a grown-up. Normally, the voice of a lady has a higher frequency than that of a man.

Audible and Inaudible Sounds:

For the human ear, the range of audible frequencies is roughly from 20 to 20,000 Hz. Sounds outside this range are inaudible. Some animals like dogs can hear sounds of frequencies higher than 20,000 Hz. 

Noise and Music:

A few sounds are wonderful to the ear, though some are not. Terrible sounds are called Noise. Then again, Musical sound is one which is satisfying to the ear, for example, the line of a sitar gives out a melodic sound. 

Noise Pollution: 

The presence of unnecessary or undesirable sounds in the climate is called noise pollution. 

Significant reasons for noise pollution are hints of vehicles, blasts including blasting of wafers, machines, amplifiers and so on 

Loudness: 

Loudness of sound is corresponding to the square of the adequacy of the vibration creating the sound. For instance, assuming the amplitude turns out to be twice, the Loudness increments by a component of 4.

• The unit of loudness is decibel (dB).
• The table below gives some thought of the loudness of sound coming from different sources:

Over 80 dB the noise turns out to be truly painful.  

Measures to Limit Noise Pollution: Attempts should be made to minimise noise pollution at the source point such as installing silencing devices in aircraft engines, transport vehicles, industrial machines, and home appliances. Reducing noise pollution in a residential area is utmost needful and can be done by:

• Setting up the noise producing industries away from such areas.
• Minimising the use of automobile horns.
• Running TV and music systems at low volumes.

• Plantation of trees along the roads and around buildings. Some household sources of noise pollution are high volume television, some kitchen appliances, desert coolers, air conditioners, etc.

Harmful effects of Noise Pollution: Noise pollution may pose health problems for human beings such as Lack of sleep, hypertension (high blood pressure), anxiety, etc. Exposure to loud sound continuously may lead to temporary or even permanent impairment of hearing. 

In Conclusion: 

Sound is a type of energy that causes the sensation of hearing. It is also a type of energy that is generated by vibrations. These vibrations produce sound waves, which travel through mediums like air and water before reaching our ears. All sounds are made up of pure frequencies. When a stretched rubber band is plucked, it vibrates and emits sound.