CBSE Class 8 Science Chapter 13 Revision Notes

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CBSE Class 8 Science Chapter 13 Sound Revision Notes

CBSE Class 8 Science Chapter 13 Sound Revision Notes are by far the best and most reliable Revision Notes for Sound. These CBSE Class 8 Science Chapter 13 Sound Revision Notes provided here are prepared by our subject experts at Swiflearn to help students to recall important concepts and points related to Chapter 13 Sound of CBSE Class 8 and in turn, enhance their confidence.

CBSE Class 8 Science Chapter 13 Sound Revision Notes will surely make your learning convenient & fun. Students can download CBSE Class 8 Maths Chapter 13 Sound Revision Notes in PDF format, use them to retain their previously learned concepts, and hence, ensure better examination results for themselves.


Production of sound waves

Sound or sound waves are generated or produced by different sources.

▪ A sound is produced by a vibrating body. The to and fro or back and forth motion of an object is termed as vibration.
▪ When a body vibrates, it produces sound in the surrounding medium.
▪ The vibrations are transferred to the medium surrounding the sound source.
▪ When the vibrations propagate away from the source, they form a sound wave. The speed at which they moved is called the speed of sound.
▪ In most cases, the amplitude of vibrations is so small that we cannot hear them. However, we can feel the vibrations if we come in contact with the vibrating body.



▪ You can feel the vibrations of the diaphragm stretched over speakers.
▪ A tightly stretched band when plucked, vibrates and produces sound.


Sound Produced by Humans

In humans, the sound is produced by the voice box or the larynx.

▪ The voice box is at the upper end of the windpipe.
▪ Two vocal cords are stretched across the larynx in such a way that it leaves a narrow slit between them for the passage of air.
▪ When the lungs force air through the slit, the vocal cords vibrate and produce sound.
▪ The type and quality of voice produced differ in each human being. It depends on the tightness and the thickness of the vocal cords.
▪ Adult male vocal cords are larger than females and are between 17 mm to 25 mm in length. Hence, male voices are usually lower-pitched.
▪ Female vocal cords are between 12.5 mm to 17.5 mm in length. Hence, women’s voices are higher in pitch.
▪ Children’s vocal cords have very short vocal cords.


CBSE Class 8 Science Chapter 13 Sound Revision Notes PDF



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