3 - 13 Sound
● ***ALL sound waves are longitudinal, can ALL be reflected, refracted & diffracted
○ Longitudinal (縱) - direction of vibration (of medium[s]) parallel to
direction wave\energy travels
Sound waves
● Sounds - produced by vibrating objects
○ We hear sounds when vibrations (travelling as sound waves) reach our ears
● ***Sound travels fastest in solids + high temperatures
● Slower than light waves
○ In air - ≈340 m/s (varies with temperature)
Reflection (反射) - echoes produced
● ***Sound waves behave like light waves, i.e.: when reflected from surface, i = r
●
Refraction (折射)
● E.g.: if sound wave travelling through warm air, travels faster than in cooler air
● ALSO waves bent from straight path when travelling through different media
● ***Change in media → speed + direction
1
● ***ALL sound waves are longitudinal, can ALL be reflected, refracted & diffracted
○ Longitudinal (縱) - direction of vibration (of medium[s]) parallel to
direction wave\energy travels
Sound waves
● Sounds - produced by vibrating objects
○ We hear sounds when vibrations (travelling as sound waves) reach our ears
● ***Sound travels fastest in solids + high temperatures
● Slower than light waves
○ In air - ≈340 m/s (varies with temperature)
Reflection (反射) - echoes produced
● ***Sound waves behave like light waves, i.e.: when reflected from surface, i = r
●
Refraction (折射)
● E.g.: if sound wave travelling through warm air, travels faster than in cooler air
● ALSO waves bent from straight path when travelling through different media
● ***Change in media → speed + direction
1
