Sources and Properties of Sound

Different sounds are heared when the sound waves travel through a medium and reach our ears. There are different natural and artificial sources of sounds. Rustling leaves produces pleasant sound, whereas car horns makes unpleasant sound. In this concept, the students will understand how is sound produced and how it travels.

After reading the concept, students will be able to:

• Explain what is sound.
• Categorise man-made and natural sources of sound.
• Describe different properties of sound.
• Compare vibrations and pitch of sound.
• Discus how do humans produce sounds.
• Recite the importance of larynx, speech box and vocal cords in producing the sounds.

Each concept is explained to class 4 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept Sources and Properties of Sound provided in PDF format.

 

 

Sources of aound:

Sources of sound can be divided into two types—

1. Natural Sources of Sound:

These sources can produce sound naturally.

Examples:

2. Man-made/Artificial sources of sound:

These are sources of sounds that man artificially makes.

Examples:

 

Pleasant and unpleasant sounds:

Sounds that make us feel happy and are pleasing to our ears are called pleasant sounds, whereas sounds that are uncomfortable to hear, cause irritation and may lead to temporary hearing impairment when heard continuously for a long time are called unpleasant sounds.

 

How Do Humans Produce Sounds?

• There are specific components in our body that help us make sounds.
• The larynx, also called the speech box, generates sound.
• The larynx is situated at the top of the windpipe in our throat.
• There are two ligaments in the larynx, called the vocal cords.
• Stretching of vocal cords allows us to make sounds.
• The vocal cords are connected to muscles that change the stretching of the cords. The muscles also change the space between the cords.
• Air is passed between the two vocal cords with the help of the lungs.
• As a result, the vocal cords start vibrating, thereby producing sound.
• The sounds are made by the vibration of the vocal cords caused by the expelled air.
• When the vocal cords are stretched, we make high sounds, and when the cords are relaxed, we make low sounds. This is known as the pitch of the sound.

 

Properties of Sound:

Amplitude and Pitch:

• Amplitude measures the loudness or quietness of a sound.
• Pitch denotes how high or how low a sound is.

• A high pitch sound has more vibrations, but a low pitch sound has fewer vibrations.

 

Interactions of sound with objects:

Sound waves can interact with objects in the following ways—

1. Reflection:

• When sound waves strike a surface and then bounce off, it is called a reflection of sound.

Examples: A very common example of the reflection of sound is the occurrence of echo. It is nothing but the repetition of sound caused due to the reflection of the sound waves.

2. Absorption:

• When sound waves get absorbed, instead of getting reflected by a sound-absorbing material, it is called absorption of sound.

Examples: Sound absorbing materials are installed in cinema halls, auditoriums, etc. so that the loud noise created in that space is not heard from outside.

 

New Words:

 

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