Lakhmir Singh Solutions Class 8 Science Chapter 13 Sound
Lakhmir Singh Solutions Class 8 Science Chapter 13 Sound is one of the most useful resources for students who want to understand the chapter simply and effectively. Sound is a common part of daily life, but this chapter explains scientifically how sound is produced, how it travels, and how we hear it. By studying this chapter carefully, students can score well in exams and improve conceptual clarity. If you are searching for complete chapter-wise help, visit Lakhmir Singh Solutions Class 8 Science for all chapters. You can also explore more resources at Lakhmir Singh Manjit Kaur Solutions.
This chapter focuses on vibrations, sound waves, the human voice, the hearing process, audible and inaudible sounds, noise pollution, and preventive measures. It is an important chapter because many real-life examples, such as musical instruments, microphones, loudspeakers, and communication systems, are based on sound.
Download the PDF of Lakhmir Singh Solutions Class 8 Science Chapter 1 3
Important Topics Covered in Chapter 13 Sound
1. What is Sound?
Sound is a form of energy that creates the sensation of hearing in our ears. It is produced when an object vibrates. For example, a ringing bell, drum, guitar string, or buzzing bee all produce sound due to vibrations.
When an object vibrates, it disturbs nearby particles and creates sound waves.
2. Sound is Produced by Vibrating Objects
The main concept of this chapter is that all sounds are produced by vibrating bodies. If there are no vibrations, no sound is produced. Examples include:
- Guitar strings vibrate to make music
- Drum membrane vibrates when struck
- Tuning fork vibrates after hitting
- Human vocal cords vibrate while speaking
This concept is frequently asked in exams.
3. Sound Needs a Medium to Travel
Sound cannot travel through vacuum because it requires particles for transmission. It can travel through:
- Solids
- Liquids
- Gases
Sound travels fastest in solids and slowest in gases because particles are closer in solids.
4. Human Voice and Larynx
Humans produce sound using the voice box called the larynx. It is located in the throat. Inside the larynx are vocal cords. When air passes through them, they vibrate and produce sound.
Children and women usually have shorter vocal cords, so their voices are shriller than men.
Characteristics of Sound
Loudness
Loudness depends on the amplitude of vibrations. Greater amplitude means louder sound.
Examples:
- Loudspeaker produces loud sound
- Whisper produces soft sound
Pitch
Pitch depends on frequency. A sound with high frequency has high pitch.
Examples:
- Flute produces high pitch
- Drum produces low pitch
Frequency
Frequency means the number of vibrations per second. It is measured in hertz (Hz).
Time Period
Time taken for one complete vibration is called time period.
Audible and Inaudible Sounds
Humans can hear sounds between 20 Hz to 20,000 Hz. This is called the audible range.
- Sounds below 20 Hz are called infrasonic sounds
- Sounds above 20,000 Hz are called ultrasonic sounds
Dogs can hear ultrasonic sounds, which humans cannot hear.
Noise and Music
- Music is a pleasant sound.
- Noise is an unpleasant sound.
Examples of noise include traffic horns, loud machines, and construction drilling.
Noise Pollution
Noise pollution means excessive unwanted sound in the environment. It can cause:
- Headache
- Stress
- Sleeplessness
- Hearing loss
- Poor concentration
Ways to Prevent Noise Pollution
- Avoid unnecessary honking
- Use silencers in vehicles
- Keep TV volume low
- Plant trees
- Use soundproof materials
- Ban loudspeakers in silent zones
Why Use Lakhmir Singh Solutions for Chapter 13 Sound?
Students prefer Lakhmir Singh Solutions because they provide:
- Easy language explanations
- Accurate answers
- Chapter-wise solved questions
- Extra practice questions
- Quick revision support
- Better exam preparation
These solutions help students understand both textbook and school exam questions clearly.
Important Exam Questions from Chapter 13 Sound
- What is sound?
- How is sound produced?
- Why does sound need a medium?
- What is pitch?
- Define loudness.
- What is noise pollution?
- What is audible range?
- Name the sound-producing organ in humans.
- Why can sound not travel in vacuum?
- State two methods to reduce noise pollution.
Revision Tips for Class 8 Science Sound Chapter
- Learn definitions properly
- Practice diagrams of ear and larynx
- Understand examples of vibration
- Revise numerical values like audible range
- Solve textbook questions daily
- Compare loudness and pitch carefully
Conclusion
Lakhmir Singh Solutions Class 8 Science Chapter 13 Sound helps students understand one of the most interesting science chapters. From vibrations to sound waves and from larynx to hearing, the chapter explains how sound plays an important role in our life. Proper practice of textbook questions and revision notes can help students score high marks easily.