Ppt on sound
- 2. PRODUCTION OF SOUND PROPAGATION OF SOUND DISTINGUISHING FACTORS OF SOUND REFLECTION OF SOUND HUMAN EAR
- 4. 2. Propagation of Sound When an object vibrates, the particles around the medium vibrate. The particle in contact with the vibrating object is first displaced from its equilibrium position. The disturbance produced by the vibrating body travels through the medium but the particles do not move forward themselves. A wave is a disturbance which moves through a medium by the vibration of the particles of the medium. So sound is considered as a wave.Sound waves Require medium for transmission. Sound waves are called mechanical waves. When a vibrating object moves forward, it pushes and compresses the air in front of it forming a region of high pressure called compression (C). When the vibrating object moves backward, it forms a region of low pressure called rarefaction (R).
- 6. There is another kind of waves called transverse waves. In these waves the particles oscillate up and down perpendicular to the propagation of the direction of disturbance. Sound propagates in a medium as a series of compressions and rarefactions. Compressions are the regions of high pressure and density where the particles are crowded and are represented by the upper portion of the curve called crest. Rarefactions are the regions of low pressure and density where the particles are spread out and are represented by the lower portion of the curve called trough
- 7. Characteristics of a sound wave
- 8. Frequency of sound wave The number of oscillations per unit time is called the frequency of the sound wave. It is represented by the symbol ٧ (Greek letter nu). Its SI unit is hertz (Hz). Time period of sound wave Frequency and time are represented as follows:- ٧ for one oscillation T = 1 v
- 9. Amplitude of sound wave The amplitude of sound wave is the height of the crest or tough. It is represented by the letter A. The SI unit is the same as that of density or pressure. The wavelength is the distance between the "crests" of two waves that are next to each other. The amplitude is how high the crests are.
- 10. Pitch and loudness of sound The pitch of sound (shrillness or flatness) depends on the frequency of vibration. If the frequency is high, the sound has high pitch and if the frequency is low, the sound has low pitch Speed of sound The speed of sound is more in solids, less in liquids and least in gases. The speed of sound also depends on the temperature of the medium. If the temperature of the medium is more, the speed of sound is more
- 11. Sound gets reflected at the surface of a solid or liquid and follows the laws of reflection. i) The angle of incidence is equal to the angle of reflection. ii) The incident ray, the reflected ray and normal at the point of incidence all lie in the same plane.
- 12. The sound waves passes through the ear canal to a thin membrane called eardrum. The eardrum vibrates. The vibrations are amplified by the three bones of the middle ear called hammer, anvil and stirrup. Middle ear then transmits the sound waves to the inner ear. The brain then interprets the signals as sound.