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42 Cards in this Set
- Front
- Back
What is the difference between compression and rarefaction of a sound wave?
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Compression is the part where air molecules are very dense (compact) and rarefaction is where molecules are very sparse
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Describe a longitudinal wave
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The particle movement is parallel to the wave movement
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Describe a transverse wave
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The particle movement is perpendicular to wave direction
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Does speed of sound travel faster or slower in hot air? Why?
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Sound travels faster in warm air because warm air is less dense than cold air
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What type of wave describes propagation of sound?
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Longitudinal waves
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In which medium does sound travel the slowest? air, helium, water, or steel
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Air moves at about 1130 fps at room temperature
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Which frequencies are able to bend around corners the easiest? Describe the wavelengths of these frequencies
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Low frequencies bend the easiest because the long wavelengths allow them to bend around corners without much attenuation
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Which unit is sound power normally expressed in?
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picowatts or pW
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Which unit is sound pressure normally expressed in?
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micropascals
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Describe the difference between spherical waves and plane waves
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As spherical waves spread, intensity falls off inversely as the square of the distance (inverse square law). There is no spreading with plane waves and no intensity change with distance
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What is sound pressure at nominal threshold? Why?
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20 micropascals, which is the average sound pressure required to reach threshold at 1000 Hz for a young adult from a screened population
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What is the main reason to use a decibel scale to express the level of sound?
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Decibels compress the large range of numbers
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What decibel change is a just noticeable difference (JND)?
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3 dB
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What decibel change is a doubling of loudness?
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10 dB
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Describe difference between periodic and aperiodic waves
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A waveform that repeats itself is periodic. An aperiodic wave includes all frequencies and does not repeat itself
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To cancel a tone, a second tone must be sounded that meets which condition?
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same frequency, same amplitude, and opposite phase
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vocal fold vibration is modeled as a periodic wave with which kind of harmonics?
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Speech contains odd and even harmonics
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What is the term for the gradual decline in the amplitude of simple harmonic motion?
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damping
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what is the formula for sound pressure level in decibels?
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20 log (P/Pr)
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What is a wave which does not encounter a reflective surface?
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free progressive wave
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What is a pure tone?
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sound from a single frequency
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What kind of noise is produced by a broad band of frequencies?
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white noise
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What occurs when the driving frequency of one system matches the natural frequency of a vibrating system?
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resonance
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What type of resonance occurs when a tuning curve is tall and narrow?
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sharp resonance
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what is the beat frequency of two tones at 2024 Hz and a 2030 Hz?
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6 Hz
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What 3 characteristics describe a filter?
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center frequency, bandwidth, attenuation rate (slope)
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What attenuation (in decibels) does the inverse square law provide?
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6 dB per doubling of distance
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What term describes when sound waves bend due to a temperature inversion?
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refraction
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What term describes when sound bends around the corner of a building?
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diffraction
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The nodes on a vibrating string are points where there is what kind of motion?
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no motion
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What type of room would a free progressive wave be found?
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anechoic room
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What is it called when the distance from a source in a room where the direct sound is equal to the reverberant sound?
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critical distance
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What is the definition of reverberation time?
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The time it takes for sound to decay by 60 dB
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What component of every vibrating system causes damping to occur? What is this force named?
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Component = resistance
Force = friction |
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The bandwidth of a filter is the difference between what 2 frequencies?
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The upper frequency cut-off and the lower frequency cut-off
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Describe the effects of concave and convex surface to sound
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Concave surface bends toward incident sound and focuses the sound and convex surface bends away and scatters the sound
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What type of room would a free progressive wave be found?
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anechoic room
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What is it called when the distance from a source in a room where the direct sound is equal to the reverberant sound?
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critical distance
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What is the definition of reverberation time?
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The time it takes for sound to decay by 60 dB
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What component of every vibrating system causes damping to occur? What is this force named?
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Component = resistance
Force = friction |
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The bandwidth of a filter is the difference between what 2 frequencies?
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The upper frequency cut-off and the lower frequency cut-off
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Describe the effects of concave and convex surface to sound
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Concave surface bends toward incident sound and focuses the sound and convex surface bends away and scatters the sound
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