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Sound class 8 Notes Science

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Sound class 8 Notes Science in PDF are available for free download in myCBSEguide mobile app. The best app for CBSE students now provides Sound class 8 Notes Science latest chapter wise notes for quick preparation of CBSE exams and school based annual examinations. Class 8 Science notes on chapter 13 Sound Science are also available for download in CBSE Guide website.

CBSE Guide Sound class 8 Notes Science

CBSE guide notes are the comprehensive notes which covers the latest syllabus of CBSE and NCERT. It includes all the topics given in NCERT class 8 Science textbook. Users can download CBSE guide quick revision notes from myCBSEguide mobile app and my CBSE guide website.

Class 8 Science notes Chapter 13 Sound

Download CBSE class 8th revision notes for chapter 13 Sound in PDF format for free. Download revision notes for Sound class 8 Notes and scores high in exams. These are the Sound class 8 Notes prepared by team of expert teachers. The revision notes help you revise the whole chapter 13 in minutes. Revision notes in exam days is one of the best tips recommended by teachers during exam days.

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CBSE Class 8 Revision Notes Science Sound

Sound:  Vibrations that travel through the air or another medium and can be heard when they reach a person’s or animal’s ear.

Musical Sound: The sound which produce a pleasing effect on the ear.

Noise: The sounds which produce a jarring or unpleasant effect.

Types of Sound:

(i) Audible Sound: Vibrations whose frequency lies between 20 Hz to 20,000 Hz (20 kHz) are heard by human ear.

(ii) Inaudible Sound: The sounds having frequencies above 20,000 Hz and below 20 Hz cannot be heard by the normal human ear.

  • Low-frequency sounds which cannot be heard are called infrasonics.
  • High-frequency sounds which cannot be heard are called ultrasonics.

In human beings, the vibration of the vocal cords produces sound.

Sound travels through a medium (gas, liquid or solid). It cannot travel in vacuum.

The eardrum senses the vibrations of sound. It sends vibrations to the inner ear. From there, the signal goes to the brain. That is how we hear.

Higher the frequency of vibration, the higher is the pitch, and shriller is the sound.

Unpleasant sounds are called noise.

Excessive or unwanted sounds lead to noise pollution. Noise pollution may pose health problems for human beings. Lack of sleep, hypertension (high blood pressure), anxiety and many more health disorders may be caused by noise pollution. A person who is exposed to a
loud sound continuously may get temporary or even permanent impairment of hearing.

Attempts should be made to minimize noise pollution. Silencing devices must be installed in aircraft engines, transport vehicles, industrial machines, and home appliances.

Plantation on the roadside and elsewhere can reduce noise pollution.

Amplitude: The maximum extent of vibration of the vibrating body from its mean position is known as its amplitude.

Time Period: One complete to and fro movement of the pendulum around its mean position is called one oscillation. The time taken by the vibrating particle to complete one oscillation is called time period.


  • The number of vibrations made by the vibrating body in one second is known as its frequency.
  • The SI unit of frequency is the hertz (Hz).

Characteristics of Sounds:

(i) Loudness: The sensation produced in the ear which enables us to distinguish between a loud and a faint sound. Larger the amplitude of vibration, the louder is the sound produced. It is proportional to square of the amplitude.

(ii) Pitch: The characteristics of sound which distinguishes between a shrill sound and a soft sound. Higher the frequency of vibration, higher is the pitch and shrillness.

(iii) Quality: Characteristic which enables us to distinguish between musical notes emitted by different musical instruments or voices even though they have the same pitch and loudness.

CBSE Class 8 Revision Notes and Key Points

Sound class 8 Notes Science. CBSE quick revision note for class-8 Science, Chemistry, Math’s, Biology and other subject are very helpful to revise the whole syllabus during exam days. The revision notes covers all important formulas and concepts given in the chapter. Even if you wish to have an overview of a chapter, quick revision notes are here to do if for you. These notes will certainly save your time during stressful exam days.

To download Sound class 8 Notes Science, sample paper for class 8 Science, Social Science, ; do check myCBSEguide app or website. myCBSEguide provides sample papers with solution, test papers for chapter-wise practice, NCERT solutions, NCERT Exemplar solutions, quick revision notes for ready reference, CBSE guess papers and CBSE important question papers. Sample Paper all are made available through the best app for CBSE students and myCBSEguide website.

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