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Production of Sound: Vibrations, Waves, and the Human Voice
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- Production of Sound: Sound is produced by striking the tuning fork, by plucking, scratching, rubbing, blowing or shaking different objects.
- We set the objects vibrating and produce sound.
- Meaning: Vibration means a kind of rapid to and for motion of an object.
- Sound Production in Human: The sound of the human voice is produced due to vibrations in the vocal cords.
- Sound is produced by the vibration of objects.
- Wave Propagation: When an object vibrates, it creates a disturbance in the surrounding medium (usually air) which propagates in the form of waves, ultimately reaching our ears.
 [Voice box in humans]
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Production of Sound by Humans: The Role of the Voice Box and Vocal Cords
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- In humans, the sound is produced by the voice box or the larynx.
- Voice box in humans is at the upper end of the windpipe.
- Two vocal cords are stretched across the voice box or 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, producing sound.
- When the vocal cords are tight and thin, the type or quality of voice is different from that when they are loose and thick.
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Propagation of Sound: Vibrations, Mediums, and Wave Dynamics
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- Sound is produced by vibrating objects.
- Required Medium: The matter or substance through which sound is transmitted is called a medium.
- It can be solid, liquid or gas.
- Sound moves through a medium from the point of generation to the listener.
- When an object vibrates, it sets the particles of the medium around it vibrating.
- The particles do not travel all the way from the vibrating object to the ear.
- A particle of the medium in contact with the vibrating object is first displaced from its equilibrium position.
- It then exerts a force on the adjacent particle.
- As a result, the adjacent particle gets displaced from its position of rest.
- After displacing the adjacent particle, the first particle comes back to its original position.
- This process continues in the medium till the sound reaches your ear.
- The disturbance created by a source of sound in the medium travels through the medium.
- Wave: It is a disturbance that moves through a medium when the particles of the medium set neighbouring particles into motion.
- Mechanical Wave: Sound waves are characterised by the motion of particles in the medium and are called mechanical waves.
- Air is the most common medium through which sound travels.
 [A vibrating object creating a series of compressions (C) and rarefactions (R) in the medium.]
- Compression: When a vibrating object moves forward, it pushes and compresses the air in front of it creating a region of high pressure. This region is called a compression (C).
- This compression starts to move away from the vibrating object.
- Refraction: When the vibrating object moves backwards, it creates a region of low pressure called rarefaction (R) .
- As the object moves back and forth rapidly, a series of compressions and rarefactions is created in the air.
- These make the sound wave that propagates through the medium.
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Sound Waves are Longitudinal waves: Longitudinal Motion and Wave Nature
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- Longitudinal Waves: In a longitudinal wave, the particles of the medium (such as air, water, or solids) vibrate in the direction of the wave’s propagation.
- This means that the motion of the particles is parallel to the direction of the wave itself.
- In the case of sound waves, air molecules move back and forth parallel to the direction in which the sound is travelling.
- The compressions and rarefactions alternate, creating a series of high-pressure (compression) and low-pressure (rarefaction) regions.
- Transverse Waves: In a transverse wave, the particles of the medium oscillate perpendicular to the direction of the wave’s motion.
- This creates crests (high points) and troughs (low points) in the wave.
- Examples of transverse waves include light waves and waves on a string.
- In light waves, the electric and magnetic fields oscillate perpendicular to the direction of propagation.
- Nature of Waves: While sound waves are longitudinal, some waves in other mediums (like water waves on the surface of a pond) can exhibit both longitudinal and transverse characteristics.
- Surface Waves: These are known as surface waves, as they have components that move both parallel and perpendicular to the direction of wave motion.
- Longitudinal Wave Only: Sound waves specifically, which travel through air or other mediums, are longitudinal waves and do not exhibit transverse motion.
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