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- – Presence of excessive unwanted noise in our surroundings is called noise pollution. – Can cause hearing impairment, sleeplessness and also hypertension. – Must be minimised by reducing noisy operations and honking in residential areas. Planting trees along roads also cuts down the noise.
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NCERT Solutions for Class 8 Science Chapter 13 Sound renders students with accurate solutions to all the exercises and in-text questions provided in the NCERT Class 8 textbook that aligns with the CBSE Board.
- The topics and subtopics present in Chapter 13 of NCERT Solutions for Class 8 Science are as follows: Sound is Produced by a Vibrating Body Sound...
- The NCERT Solutions for Class 8 Science Chapter 13 is prepared by highly experienced faculty after conducting vast research on each concept. While...
- The human ear can easily detect frequencies between 20 Hz and 20 kHz. Hence, sound waves with frequency ranging from 20 Hz to 20 kHz is known as au...
- Introduction to Sound
- Sound Properties
- Sounds by Humans
- Hearing
- Amplitude, Time Period and Frequency
- Noise Pollution
Introduction to waves
1. The sound is produced by vibrating objects. 2. They travel from one place to another in the form of waves. Hence, the name sound waves.
Wave and particle motion of waves
1. Mechanical waves are waves that travel through a material medium. 2. It is of two types: depending on the direction of motion of the particle of the medium and the wave propagation: *transverse *longitudinal
Transverse waves
1. Particle motion is to perpendicular the direction of wave motion. 2. This type of wave is a mechanical wave called a transverse wave. For example, light or even Mexican wave in a stadium.
Introduction to sound waves
– Sound needs a medium to propagate. The matter or material through which sounds propagates is called a medium. – Sound cannot travel in a vacuum. The moon does not have an atmosphere. Hence, you can hear on the moon.
How do humans produce sound?
1. The sound produced in the voice box is called the larynx, located at the upper end of the windpipe. 2. 2 vocal cords get stretched across in the voice box. Has a slit through which air is forced out by the lungs. 3. Muscles attached to vocal cords make them tight or loose.
Human ear
1. Outer ear = pinna: collects sound from the surroundings. 2. Sound passes through a tube called an auditory canal. 3. Eardrum (tympanic membrane) → vibrates when the sound incident. 4. Vibrations are sent to the inner ear, and from there, it goes to the brain as signals via the auditory nerve. To know more about Human Ear, visit here.
Amplitude, frequency and time period of vibrations
1. The magnitude of disturbance in the medium on either side of the mean value is called as Amplitude(A). Larger the amplitude, the louder the sound. 2. The number of oscillations per second is called frequency. Expressed in Hertz(Hz). 3. Time taken for one complete oscillation to travel across a point. T = 1/f. (Seconds)
Loudness and Pitch
1. Volume or loudness of a sound depends on the amplitude. The force with which an object is made to vibrate gives the loudness. 2. The number of oscillations per unit time. Directly proportional to frequency.
Audible and inaudible sounds
1. Audible range = 20Hz to 20kHz known as the Sonic range. 2. Below 20 Hz (inaudible) → infrasonic range 3. Above 20 kHz (inaudible) → Ultrasonic range To know more about “Characteristics of Sound Waves”, visit here.
Noise and music
– Sounds with the same pitch and loudness can be distinguished based on the quality. Music is pleasant to the ears, while noise is not. – Unpleasant sounds are called noise.
Noise pollution and measures to control it
– Presence of excessive unwanted noise in our surroundings is called noise pollution. – Can cause hearing impairment, sleeplessness and also hypertension. – Must be minimised by reducing noisy operations and honking in residential areas. Planting trees along roads also cuts down the noise. To know more about Noise Pollution, visit here. Learn more about sound and its properties and other related topics, including CBSE class 8 Science notes, at BYJU’S. Also, Read
Aug 12, 2024 · Sound cannot travel in a vacuum. The number of oscillations per second of a vibrating object is called its time period. If the amplitude of vibration is large, the sound is feeble. For human ears, the audible range is 20 Hz to 20,000 Hz. The lower the frequency of vibration, the higher is the pitch.
Noise pollution is characterised by consistently loud or unwelcome sounds. Serious health problems can arise from noise pollution. Sleep deprivation, hypertension, anxiety, and other health issues are all brought on by noise pollution. Hearing loss could be either temporary or permanent for someone who is frequently exposed to loud noises.
As the lungs throw the air out of the windpipe, it passes through the slit and hence allows the production of sound as the vocal cords start vibrating. The vocal cord muscles also play a role in the production of sound. Their thickness and tightness describe the quality or type of the voice a person has.
Answer: The vibrating object produces sound. When vibration is produced in the air, sound travels from one place to another in the form of disturbance of the air particles. For propagation from one place to another, sound needs a medium (gas, liquid or solid). It cannot travel in a vacuum.
Jun 13, 2024 · How do humans produce sounds. Human ear. Amplitude, frequency, and time period of vibrations. Audible and inaudible sound. Noise pollution. NCERT Solutions For Class 8 Science Chapter 13 PDF.
