1. Chapter 21 - The Nature of Sound

2. Sound is produced by ________________ which are the complete _____________________ motion of an object Sound travels as __________________ waves, where the particles vibrate back and forth _________________________ that the wave travels. Sound waves travel ________________________ from their source, but the ____________ through which they pass does ________ travel. The particles in the media just ____________ back and forth. vibrations back and forth longitudinal along the path in alldirections medium NOT vibrate Sound waves require a ___________. Usually this is ____ but sound waves also travel through ___________, ____________, and __________. Sound cannot travel in a _________. mediumair water glassmetal vacuum

3. Properties of Sound The speed of sound through any ___________ is ___________ unless the properties of the medium change. mediumconstant 1. The ____________ the medium, the ____________ the speed of sound. Why? _____________________________ _______________________________________________ cooler slower The particles in cool materials move slower and therefore transmit energy more slowly. This is a picture of a jet breaking the sound barrier (traveling faster than the speed of sound). Pitch - how _______ or _________ you perceive a sound to be. This depends on the __________________ of a wave (the _____________ of waves produced in a given time, expressed in ____________). high low frequency number hertz (Hz) When an object goes faster than the speed of sound, it breaks the ________ ________, causing ________ ___________ which we hear as a __________ ________. sound barrier shock waves sonic boom

4. Humans can hear sound frequencies between ____________ and _____________ Hz. Sounds below 20 Hz are ____________ and sound above 20,000 Hz are ______________. Most humans cannot hear sounds in these ranges. 20 20,000infrasonic ultrasonic The Doppler Effect - the ________________ change in the ________________ of a sound caused by ____________ of either the _____________ or the _____________ of the sound. apparent frequencymotion listener source

5. Loudness is how_______ or __________ a sound is, and depends on the amount of _____________ transferred, which affects the _______________ particles in the medium move from their ______ position. A. The _________________ is the maximum distance the _______________in a wave vibrate from their ________ position. The ____________ the amplitude, the __________ the sound. B. Loudness is measured in ______________. The human ear can hear from ______ and feels pain at ________. loudsoft energy distancerest amplitude particlesrest largerlouder decibels (dB) 0 dB120 dB An ________________ can convert sound waves into a graphic representation showing ________________ and _______________ of the wave. oscilloscope amplitude frequency low amplitudehigh amplitude high frequency low frequency same frequency

6. Interactions of Sound Waves Reflection - _________________________________________ ____________________________________________________ This is called an _________. The amount of reflection depends on the reflecting _____________. Waves reflect best off of __________, _____________ surfaces. The bouncing back of sound waves after striking a barrier echo surface smooth hard Interference - _______________________________________ A. Constructive interference - _______________________ _______________________________________________ B. Destructive interference - ________________________ _______________________________________________ The result of 2 or more waves overlapping As the compressions of one wave overlap the compressions of another wave, the sound will be louder because the amplitude is increased. As the compressions of one wave overlap the rarefractions of another wave, the sound will be softer because the amplitude is decreased. C. Standing waves - ______________________________ _______________________________________________ Interference in which portions of the wave are at rest and others have large amplitude.

7. Resonance - ___________________________________________ _______________________________________________ An object vibrating at or near the resonant frequency of another object causes the second object to vibrate Resonant frequencies - _________________________________ ____________________________________________________ The frequencies at which standing waves are made

8. Sound quality - _______________________________________ ____________________________________________________ the result of several pitches blending together through interference Noise Sound of speech

9. Chapter 21 - The Nature of Sound

10. Sound is produced by ________________ which are the complete _____________________ motion of an object Sound travels as __________________ waves, where the particles vibrate back and forth _________________________ that the wave travels. Sound waves travel ________________________ from their source, but the ____________ through which they pass does ________ travel. The particles in the media just ____________ back and forth. Sound waves require a ___________. Usually this is ____ but sound waves also travel through ___________, ____________, and __________. Sound cannot travel in a _________.

11. Properties of Sound The speed of sound through any ___________ is ___________ unless the properties of the medium change. 1. The ____________ the medium, the ____________ the speed of sound. Why? _____________________________ _______________________________________________ This is a picture of a jet breaking the sound barrier (traveling faster than the speed of sound). Pitch - how _______ or _________ you perceive a sound to be. This depends on the __________________ of a wave (the _____________ of waves produced in a given time, expressed in ____________). When an object goes faster than the speed of sound, it breaks the ________ ________, causing ________ ___________ which we hear as a __________ ________.

12. Humans can hear sound frequencies between ____________ and _____________ Hz. Sounds below 20 Hz are ____________ and sound above 20,000 Hz are ______________. Most humans cannot hear sounds in these ranges. The Doppler Effect - the ________________ change in the ________________ of a sound caused by ____________ of either the _____________ or the _____________ of the sound.

13. Loudness is how_______ or __________ a sound is, and depends on the amount of _____________ transferred, which affects the _______________ particles in the medium move from their ______ position. A. The _________________ is the maximum distance the _______________in a wave vibrate from their ________ position. The ____________ the amplitude, the __________ the sound. B. Loudness is measured in ______________. The human ear can hear from ______ and feels pain at ________. An ________________ can convert sound waves into a graphic representation showing ________________ and _______________ of the wave. low amplitudehigh amplitude high frequency low frequency same frequency

14. Interactions of Sound Waves Reflection - _________________________________________ ____________________________________________________ This is called an _________. The amount of reflection depends on the reflecting _____________. Waves reflect best off of __________, _____________ surfaces. Interference - _______________________________________ A. Constructive interference - _______________________ _______________________________________________ B. Destructive interference - ________________________ _______________________________________________. C. Standing waves - ______________________________ _______________________________________________

15. Resonance - ___________________________________________ _______________________________________________ Resonant frequencies - _________________________________ ____________________________________________________

16. Sound quality - _______________________________________ ____________________________________________________ Noise Sound of speech