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Reflection and Absorption. F 66-72. Do sounds bounce?. Reflection the bouncing of a sound wave off a surface Some of the wave’s energy enters the surface and some of the sound will disappear This disappearance is called absorption
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Reflection and Absorption F 66-72
Do sounds bounce? • Reflection the bouncing of a sound wave off a surface • Some of the wave’s energy enters the surface and some of the sound will disappear • This disappearance is called absorption • When a sound wave is absorbed its energy is changed into heat energy
What is an Echo? • Echo a reflected sound wave • Made when a sound wave hits a surface and the sound is reflected back to the listener • Echolocation a form of sonar used by some animals (ex. Whales and dolphins) the sound waves bounce off of objects and the animals can tell how far away from a given object they are
An echo is a copy of the original sound; both the original sound and the echo will have the same pitch
Approaching Sound As a siren approaches, there are more sound waves reaching your ear each second than if the police car were standing still • The frequency increases and the pitch is higher
Departing Sound • As the siren moves away, the sound waves spread out • The frequency decreases and the pitch is lower
Change in Frequency • Doppler effect the change in frequency (and pitch) as a source of sound moves toward or away from you • Many radar devices use this effect to find the speed of an object
What is Fundamental Frequency? • Quality sound is what makes it different from another sound of the same loudness and pitch • makes the sound unique • Fundamental Frequency the lowest frequency at which something will vibrate • Overtones sections of vibrating at higher frequencies each with a different pitch • It is F.F. and O.T. that give a sound its own quality
Resonance • The natural frequency of a vibration • If a vibrating force shakes from natural frequency, the vibration builds up • Can make a trumpet or violin louder • Can cause damage to buildings and bridges