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Speech Science
03 Physics of Sound- Wave length and resonance
Term | Definition |
---|---|
period of a sound | the duration of one cycle of vibration |
wavelength | the physical distance in space one cycle occupies |
Speed of sound | 1130 feet per second(344 meters per second) |
If a 1000 Hz tone has 1000 cycles per second, and that sound wave travels at a rate of 1130 feet per second, what isthe distance one cycleoccupies (what is its wavelength)? | 1130 feet/sec 1000 cycles/sec= 1.13 ft (wave length) |
formula for wave length | =Speed of sound/ frequency of wave (aka # of cycles/sec) |
What is the wavelength of a 2000 Hz tone? | 1130 feet-sec/ 2000 cycles-sec = 0.565 ft. |
What is the correlation between wave length and frequency? | Lower the frequency longer the wave length. |
What is the wavelength of a 250 Hz tone? | 1130 ft-s /250 cycles-s= 4.52 ft |
What is the wavelength of a 6000 Hz tone? | 1130 ft/sec = .188 ft 6000 cycles/sec |
What is the wavelength of a 500 Hz tone? | 1130 ft-sec/500 cycles/sec = 2.26 ft |
What is the frequency of a tone that has a wavelength of 2.825 ft.? | 1130 ft-s/2.825 ft= 400Hz |
What is the frequency of a tone that has a wavelength of 9.04 ft? | 1130/9.04= 125 Hz |
What is the frequency of a tone that has a wavelength of 5.65 ft? | 1130/5.6= 200Hz |
What is the wavelength of a tone that has a period of 0.2 ms? | 1) Find frequency- 1s/.0002s= 5000 HZ 2) Find wave length- 1130/5000=0.226 ft |
Resonance | Is sound reflection |
Echo | - occurs when sound is reflected off a distant surface - the reflecting sound is heard after it is produced |
Reverberation & Resonance- | -occur within smaller, enclosed spaces where the sound bounces from wall to wall while the sound is being produced -As sound is reflected from wall to wall within a small room, the reflected sound enhances the original sound source |
When reverberation becomes resonance | -As the enclosure becomes smaller, the sound energy bounces around much more rapidly within the container causing it to “ring” -When the enclosure reaches a certain smallness, its “ringing” will dominate the sound source, reverberation becomes resonance |
Reverberation makes sound seem | fuller |
Resonance makes sound | seem louder, more intense |
Low frequency notes reverbertae in what type of containers? | long |
high freq notes reverberate in what type of container? | short |
A tube, open at one end, rings best (resonates) | -at the frequency having a wavelength that is 4 times the length of the tube -and at odd number multiples of this frequency |
At what frequencies will a 1ft, open ended tube resonate? | Wave length= 4 x length of tube Wave length= 4 X 1 WL= 4ft 1130 feet-sec/ 4 feet = 282.5 Hz Tube will resonant at 282.5 Hz and at odd number multiples of this frequency 282.5 X 1 = 282.5 Hz 282.5 X 3 = 847.5 Hz 282.5 X 5 = 1412.5 Hz |
At what frequencies will a 3 ft, open ended tube resonate? | 1) WL= 4x length of tube- 4x3= 12ft 2) 1130 ft-sec/12 ft= 94.17 HZ (freq) This tube will resonant at 94.17 Hz and at odd number multiples of this frequency |
At what frequencies will a 5 ft, open ended tube resonate? | 1) WL= 4x5=20 ft 2) 1130/20= 56.5 HZ This tube will resonant at56.5 Hz and at odd number multiples of this frequency |
What is the length of a tube that has a primary resonance of 4000 Hz? | 1) Find WL- 1130 feet-sec/4000 Hz= 0.28 ft 2) The wavelength is 4 times the length of the tube. 3) Therefore .28ft/4= .07ft |
What is the length of a tube that has a primary resonance of 750 Hz? | 1130 feet-sec/750Hz= 1.5 ft 1.5 feet/4 = 0.375 feet |