sound origin of sound nature of sound in air media that transmit sound speed of sound in air...
TRANSCRIPT
![Page 1: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/1.jpg)
Sound•Origin of Sound•Nature of Sound in Air•Media that Transmit Sound•Speed of Sound in Air•Refraction•Energy in Sound Waves•Forced Vibrations•Natural Frequency•Resonance•Interference•Beats
![Page 2: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/2.jpg)
Sound...
• ...a longitudinal wave in air caused by a vibrating object.
• Sound requires a medium.– solid, liquid or gas– Will a bell ring in a evacuated Bell Jar?
![Page 3: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/3.jpg)
Nature of Sound in Air
• Sound waves have compression and rarefaction regions.
![Page 4: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/4.jpg)
Origin of Sound
• infrasonic – frequencies < 20 Hz
• ultrasonic
– frequencies > 20,000 Hz
• human hearing range – frequencies between 20
Hz and 20,000 Hz
![Page 5: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/5.jpg)
Speed of Sound in Air
• 340 meters/second
• 760 miles/hour
• Mach 1
![Page 6: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/6.jpg)
increases with humidityincreases with temperatureincreases with density
How it varies:
SPEED OF SOUND
![Page 7: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/7.jpg)
What is the approximate distance of a thunderstorm when you note a 3 second delay between the flash of the lightning and the sound of the thunder?
Lightning and Thunder
![Page 8: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/8.jpg)
What is the approximate distance of a thunderstorm when you note a 3 second delay between the flash of the lightning and the sound of the thunder?
Answer: 3 seconds 340 meters/second
= 1020 meters
![Page 9: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/9.jpg)
Acoustics...
• ...the study of sound properties.
• When a sound wave strikes a surface it can be.…– (a) reflected.
– (b) transmitted.
– (c) absorbed.
– (d) all of these.
![Page 10: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/10.jpg)
Acoustics...
• ...the study of sound properties.
• When a sound wave strikes a surface it can be.…– (a) reflected.
– (b) transmitted.
– (c) absorbed.
– (d) all of these.
![Page 11: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/11.jpg)
Reflection of Sound
• e.g. an echo • Reverberation - re-echoed sound,
multiple reflections of sound waves from walls
• Compare reflections from a hard wall with that from a carpet wall.
![Page 12: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/12.jpg)
Refraction of Sound
• Refraction - the bending of a wave
• Sound travels faster in warm air than in cool air.
• Sound waves bend toward cooler air.
![Page 13: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/13.jpg)
![Page 14: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/14.jpg)
• Subsonic - slower than the speed of sound• Supersonic – faster than the speed of sound
Mach Number =speed of sound
speed of object
Speed of Sound
![Page 15: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/15.jpg)
Forced Vibrations/Resonance
• …the setting up of vibrations in an object by a vibrating force.
• Examples of Forced Vibration:– A tuning fork touching a wood surface
– Sounding boards for stringed instruments
– Matching tuning fork boxes
![Page 16: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/16.jpg)
• During forced vibration sound is intensified because a larger surface area is available to vibrate air molecules.
![Page 17: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/17.jpg)
Resonances
![Page 18: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/18.jpg)
Sound Interference
• Overlapping compressions of a sound wave will result in…– …constructive interference.
– …and a louder sound.
• Overlapping a compression and a rarefaction results in... – …destructive interference.
– …and a softer sound.
![Page 19: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/19.jpg)
![Page 20: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/20.jpg)
Constructive InterferenceDestructive Interference
![Page 21: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/21.jpg)
Sound Interference
• Noise reduction headphones• Echo cancellation
![Page 22: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/22.jpg)
• Beats - the periodic variation in loudness of two sounds played together
• The beat frequency is equal to the difference in the frequency of the two sounds.
Beats
![Page 23: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/23.jpg)
For the same temperature for air, does sound travel faster in humid Galveston or in dry El Paso?
(a) Galveston
(b) El Paso
(c) same speed in either city
![Page 24: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/24.jpg)
For the same temperature for air, does sound travel faster in humid Galveston or in dry El Paso?
(a) Galveston
(b) El Paso
(c) same speed in either city
![Page 25: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/25.jpg)
The bending of sound through air of uneven temperature is called
(a) reflection
(b) refraction
(c) interference
(d) reverberation
(e) resonance
![Page 26: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/26.jpg)
The bending of sound through air of uneven temperature is called
(a) reflection
(b) refraction
(c) interference
(d) reverberation
(e) resonance
![Page 27: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/27.jpg)
Lightning is seen, then ten seconds later thunder is heard. Approximately, how far away in meters is the thunder cloud?
(a) 10,500 m
(b) 5280 m
(c) 1050 m
(d) 3400 m
(e) 680 m
![Page 28: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/28.jpg)
Lightning is seen, then ten seconds later thunder is heard. Approximately, how far away in meters is the thunder cloud?
(a) 10,500 m
(b) 5280 m
(c) 1050 m
(d) 3400 m
(e) 680 m
![Page 29: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/29.jpg)
A 250 Hz tuning fork and a 260 Hz tuning fork are vibrating near each other. How many beats per second are heard?
(a) 255
(b) 510
(c) 10
(d) 250
(e) 260
![Page 30: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/30.jpg)
A 250 Hz tuning fork and a 260 Hz tuning fork are vibrating near each other. How many beats per second are heard?
(a) 255
(b) 510
(c) 10
(d) 250
(e) 260
![Page 31: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/31.jpg)
Musical Sounds
![Page 32: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/32.jpg)
Noise Versus Music
• What is the difference between noise and music?
– Answer: The appearance of the waveform.
Mac Mic
![Page 33: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/33.jpg)
NOISE VERSUS MUSIC
![Page 34: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/34.jpg)
Same Note - Different Instrument
![Page 35: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/35.jpg)
• Harmonic– a partial tone that is an integer multiple of the fundamental
frequency
• Fundamental Frequency– the lowest frequency of vibration
– a.k.a. the first harmonic
![Page 36: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/36.jpg)
![Page 37: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/37.jpg)
![Page 38: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/38.jpg)
![Page 39: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/39.jpg)
BackBack
![Page 40: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/40.jpg)
Sound Intensity and Loudness
• Intensity of Sound
– refers to the amplitude of the pressure variations in the sound wave
![Page 41: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/41.jpg)
• Loudness
– the physiological sensation directly related to the sound intensity
– measured in bels
– 1bels = 10 decibels
![Page 42: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/42.jpg)
• Loudness
– A sound of 10 decibels is or 101 or 10 times as intense as 0 decibels.
– 20 decibels is 102 or 100 times the intensity 0 decibels.
– How much more intense is sound at 100 dB than sound at 50 dB? • Answer: 100000 times
![Page 43: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/43.jpg)
Source of Sound Loudness (db)
Threshold of Hearing 0
Conversation 60
Ear Damage Begins 85
Amplified Music 110
Jet Airplane at 30 meters 140
![Page 44: Sound Origin of Sound Nature of Sound in Air Media that Transmit Sound Speed of Sound in Air Refraction Energy in Sound Waves Forced Vibrations Natural](https://reader036.vdocuments.site/reader036/viewer/2022062321/56649e425503460f94b35a27/html5/thumbnails/44.jpg)
Common Sound Intensities
Source of Sound Intensity (W/m2) Sound Level (db)
Jet 30 m away 102 140
Air-raid siren, nearby 1 120
Disco music, amplified 10-1 110
Riveter 10-3 90
Busy street traffic 10-5 70
Conversation in home 10-6 60
Quiet radio in home 10-8 40
Whisper 10-10 20
Rustle of leaves 10-11 10
Threshold of hearing 10-12 0