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57 Cards in this Set
- Front
- Back
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Acoustics
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the study of sounds
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Amplitude
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the amount or magnitude of displacement from the position of rest
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Displacement
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a change in the position of a body in space in a particular direction
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Frequency
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time rate of periodic vibration; the number of cycle of vibration
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Medium
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a surrounding substance or mode by which energy travels
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Position Of Rest
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a state of equilibrium
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Sinusoid
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sound that contain only one frequency
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The Speech Chain
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a speaker
a medium a listener |
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Time
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the overall interval of a signal from onset to termination
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Sound
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a disturbance of particles in an elastic medium
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Signal Source
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any device that oscillates to produce sound
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Amplitude
Frequency Total Time |
Loudness
Pitch Duration |
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Complex Harmonic Motion
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a characteristic of a complex periodic vibration
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Compression
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all amplitudes above the POR
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Crest
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maximum displacement above the POR
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Period
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the amount of time created to produce one complete cycle of vibration P=1/f
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Periodic Vibration
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vibrations that repeat themselves at regular, consistent, predictable intervals
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Rarefaction
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all amplitudes below the POR
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Damping
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reflects the tendency of vibrators to decrease amplitude over time after their energy source is removed
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Trough
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maximum negative displacement below the POR
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Zero-Crossing
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intervals of zero displacement in a particular direction
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Since Curve
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a graphic representation of sinusoidal vibration over time
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As frequency increases
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Period decreases
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Larger displacement
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Greater amplitude
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Formula for a Period
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P=1/f
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How do you get a millisecond?
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multiple by 1000
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Three minimum requirements for sound
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an energy source
a signal source a medium a listener *optional |
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Energy Sources
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air
ex. breeze, wind chimes, electrical and mechanical compressors , biological bellows (lungs) |
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Mechanical Force
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a simple push and pull
ex. knocking on a door, hitting a drum |
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Sympathetic Action
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one vibrator sets another into motion ex. thunder making a window vibrate or a singer making a glass break
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Electrical
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batteries or a wall current
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Forms of a signal source
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stretched strings
elastic bands diaphragms |
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What is an everyday medium?
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Air
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Faster vibration equals
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higher frequencies
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Three graphics used for laboratory exercises
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oscillograms
power spectra spectrograms |
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Oscillograms
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defined as graphic displays of vibration amplitude over time
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Power Spectra
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graphic representations of signals as a function of amplitude and frequency
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Spectrograms
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graphic representations of vibration in three physical dimensions
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Relative intensity
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Dark-high
Light-low White-silence |
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As the period of a signal decreases
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Frequency increases
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Lightly damped sound sources
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like tuning forks, continue running freely after their energy source is removed
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Heavily damped sound sources
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lose amplitude almost immediately after their energy source is removed.
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Phase
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a portion of a cycle quantified in time or degrees
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The full phase of any cycle (in time)
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is equal to its period
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To find the quarter phase
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take full period and divide by four
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Absolute phase
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graph we learned
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Any two cycles are in-phase when
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they demonstrate identical time characteristics
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Any two cycles are out-phase when
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they demonstrate dissimilar temporal characteristics
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Relative phase
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the relationship b/t cycles
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Acoustic Summation
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the process by which signal amplitudes interact with one another at any point in a medium through algebraic summation
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Constructive Interference
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occurs when two sinusoids of identical amplitude, frequency and phase; maintain a constant in-phase time locked relationship
What occurs? a new wave with twice the amplitude |
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Standing wave
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the product of destructive interference (silence)
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Combined Interference
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occurs when two sinusoids fail to maintain a constant relationship
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Beats
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the perceived product of combined interference of two sinusoids that fail to maintain a phase-locked relationship
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Beat Frequency Phenomenon
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the product of combined interference summation
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The beat frequency is the difference between
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the two frequencies
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Standing Wave
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perceived silence
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