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142 Cards in this Set
- Front
- Back
- 3rd side (hint)
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The formula for period is:
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T (ms)= 1/f(Hz)
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________ is the amount of time it takes to complete one cycle.
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period
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________ is how fast an object is vibrating (the rate of the back & forth motion). Measures cycles per second.
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frequency (Hz)
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______ is sound with energy at only one frequency.
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simplest sound (simple harmonic motion)
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The longer the period the higher the frequency, the shorter the period the lower the frequncy. T or F?
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False
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The higher the frequency, the shorter the wavelength. T or F?
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True
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________ is the maximum amount of displacement occuring at the peak of the waveform.
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peak amplitude
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________ is the measurement from maximum point to minimum point (or 2x peak amplitude).
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peak-to-peak amplitude
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________ is the amount of amplitude occuring at any one point on the waveform.
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instantaneous amplitude
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Two amplitudes can have the same pitch. T or F?
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True
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________ is the position within a cycle relative to zero crossing (representing the circle as a sine wave).
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phase
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In a phase, the _______ corresponds to the peak amplitude.
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radius
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In a phase, the ______ corresponds to the peak-to-peak amplitude.
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diameter
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______ the amount of time to complete one full cycle or revolution.
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period (s)
T = 1/F |
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______ is a linear motion of a phase.
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sine wave
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Illustrating different degrees of phase is useful when
comparing more than 1 sound occuring at the same time. T or F? |
True
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_______ total amount of time the object vibrates; how long the vibration lasts from the first cycle to the final one.
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duration
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How many ways to graphically represent simple sounds? And what are they called?
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Two. Waveform and spectrum.
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What is the difference bw a waveform and a spectrum? And their units?
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Waveform looks like a wave with y = amp (dB), x = time(s).
Spectrum looks like a graph with y = amp (dB), x= freq (Hz)......y = phase (s), x = freq (Hz) |
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_________ an ongoing sound >ms, composed of numerous sounds, that are produced simultaneously, but have different wavelengths & amplitudes.
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complex sound
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______ is described as complex, regular, and repeating.
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complex periodic sound (harmonic)
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(examples: harmony, mosquitos)
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1) Vibrating sound that produces multiple simple periodic sounds simultaneously.
2) The frequencies & amplitudes of the simple periodic sounds are mathematically related. 3) Gives the precept idea of having a dominant tone or pitch. |
complex periodic sound
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These are the 3 properties of __________ (examples: harmony, mosquitos)
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Complex periodic sound is a series of pure tone with a frequency and amplitude. T or F?
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True
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Complex periodic sound has an infinite series of pure tone. T or F?
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True
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In a complex periodic sound, the sound source is vibrating with a fundamental frequency, and can be measured in total number of cycles. T or F?
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True
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Each component simple periodic sound (pure tone) is called a ________ .
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harmonic
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Blended together, we hear one tone.
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A naturally occuring complex periodic sound has an infinite number of harmonics. T or F?
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True
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The amplitude spectrum (graph) of a complex periodic sound has a curve to it, highest to lowest with a fundamental frequency. What are the axis/units?
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y = amp (dB)
x = freq (Hz) |
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The relationship among the harmonics of a complex periodic sound was discovered by _______.
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Jean-Baptiste Fourier, a mathematician.
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What is the Fourier Analysis? How would you explain it in your own words?
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The Fourier Analysis is a mathematical formula that provides a way to tease apart the elements of complex sound: frequencies (Hz), amplitudes (dB), and phases (s).
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What is Fourier's Theorem? How would you describe it in your own words?
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"Given any periodic motion having a fundamental frequency n, the same motion can be reduced to one particular set of simple harmonic motions of suitable amplitudes and phases whose frequencies are n, 2n, 3n, etc."
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What is the highest amplitude and the lowest frequency harmonic in a harmonic series (Fourier series)?
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The first harmonic, f0, or the fundamental frequency.
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Each subsequent harmonic has a frequency that is an integer multiple of the fundamental frequency. What does this mean?
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When calculating:1x fundamental frequency (f0), 2 x f0
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_________ an irregular and unpatterned series of component sounds that are produced simultaneously.
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complex aperiodic sound
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1) Complex aperiodic sound sources are random, chaotic.
2) The sounds have no predictable (lawful) relationship with amps (dB), phases (s), and wavelengths (m). C) Precept idea sounds like noise (acoustic term). |
complex aperiodic sound
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These are the 3 characteristics of ______.
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_______ is a singular sound, non-vibrating, has one sound wavelength (m), low/high amp (dB), no frequency (Hz), and not repeated.
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Transient, simple aperiodic sound.
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What is a transient aperiodic simple sound?
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It is a singular sound, non-vibrating, has one sound wavelength (m), low/high amp (dB), no frequency (Hz), and not repeated. > 1 ms
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What is noise?
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Noise are pressure waves, different amp (dB), frequency (Hz), phase (s). Examples: white noise, ssss, buzz, restaurant crowd.
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________ is a physical measurement of intensity. (power per unit area: watts per square meter).
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amplitude
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1 x 10^-12 watts/m^2 .......is ________
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the threshold of hearing in intensity
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The threshold of hearing is the softest sound that can be heard by a human ear. T or F
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True
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_______ is the primary unit when measuring sound levels.
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decibel (dB)
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A ratio scale gives a bigger range of represented values than a linear scale. T or F
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True
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Base -10 logarithms are also called common logarithms and are used in math and science. T or F.
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True
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_________ is power per square meter (watts/cm^2), which is another way of saying "work, or energy flow, per unit of area per unit of time" or how much energy is in a sound wave at any point in time.
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sound intensity
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_________ is force per square meter (pascals) which is another way of expressing the amplitude of a sound wave at any distance from the sound source.
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sound pressure
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If the pressure is doubled, the power becomes four times as great. T or F
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True
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Know the formula to calculate dB IL (intensity level)
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10 log (output/reference)^2
Reference for intensity: 10^-16 watts/cm^2 |
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A small change in pressure causes a larger change intensity. T or F
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True.
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The greater the intensity the greater the pressure. T or F
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True
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If intensity changes, pressure will change by the SQUARE of the same amount. T or F
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True
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20 log (output/reference) ......calculates ________.
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sound pressure level (dB SPL)
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Sound intensity decreases as distance (m) increases. T or F
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True
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Intensity varies inversely with the square of the distance. What is the ratio?
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1/4 dB or -.6 dB
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________ measures impedance.
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rayls
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Reflection occurs when the sound wavelength is smaller than the object that it encounters and results in a _______ __ _______.
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shadow of sound
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_________ is when sound encounters a high impedance & when the sound wavelength is smaller than the object it encounters results in a shadow of the sound.
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reflection
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Reflection. Consequently high frequency sounds are reflected more than low frequency sounds due to short wavelengths. T or F
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True
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________ when sound occurs as sound dissipates energy is lost due to friction between the molecules.
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absorbed
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______ sound is energy that successfully passes from one medium to another without being affected.
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transmitted (.13 sound of air transmitted thru water)
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___________ or a "bending" of the sound occurs when the wavelength of the sound is greater than the size of the object it encounters.
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diffraction
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Physical Measurements: What are the three basic quantites measured in sound?
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distance (m), mass (kg), time (s)
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Speed = Distance/time
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s = d/t
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accel = change in speed/time
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a = s-s/t
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Force = mass*accel
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F = ma
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Pressure = force/area
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p = f/a
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Work = Force*Distance
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W = FD
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Power = Work/time
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Po = W/t
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Derive: P = F/A
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Pressure = Force/Area
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P. 14
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Unit of Pressure (MKS)
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Pascals (Pa)
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Unit of Force (MKS)
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Newton (N)
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_____ is energy at rest.
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potential energy
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_____ is energy in motion.
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kinetic energy
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Acoustical, mechanical, electrical, thermal, solar, hydro are _________.
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different types of energy
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Nature of Sound: What are the two properties that all sound sources have?
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mass and elasticity.
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________ is characterized by its amount of weight and density.
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mass
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_______ is all the particles that make up that object.
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density
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________ is the ability to recover from distortion of shape or volume. It also attempts to return an object to its equilibrium or resting state.
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elasticity
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An object may exhibit an elastic limit from which it can recover. T or F
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False. cannot
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Elasticity is inversely proportional to ________ .
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stiffness, E = 1/S
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_________ is a repeated back and forth motion.
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vibration
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__________ is when a force must be exerted on an object, it also means that an object in motion stays in motion or at its current state.
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inertia
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_______ ______ causes a vibration to stop, also known as damping.
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frictional force
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Vibration results from the interplay of what two opposing forces?
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inertia and elasticity
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What are the two types of vibration?
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free vibration - an object will vibrate forever due to inertia & elasticity.
damped vibration - an object will eventually stop due to friction. |
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________ (E) refers to the at-rest position of the string, when there is no motion or vibration.
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equilibrium
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_______ causes the string or object to move away from its resting position equilibrium.
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force
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_______ is distance displaced from equilibrium.
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amplitude
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______ is porportional to force applied.
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amplitude
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__________ is the vibration of air molecules that have been set into motion by a sound source.
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sound
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Sound travels in alternating waves of _____ and ______ air.
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compressed and rarefied
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The speed of sound is a constant _______ .
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350 m/s
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A propoagating medium must have ______ and _______.
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mass (density) and elasticity
examples: air, steel, water |
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lambda (m) = c / f
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measures wavelength (m)
c = speed of sound (m/s) f = frequency (Hz) |
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________ measures the distance bw successive compressions or rarefactions.
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wavelength (lambda, m)
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______ is a doubling of the frequencies.
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octave
(2, 4, 8, 16) |
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20 micropascals or 2 x 10^-5 Pa ..............is ________.
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the threshold of hearing in pressure
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A harmonic series can be divided into octaves using a log frecuency scale with a base of __, where "n" is the number of octaves.
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2, 2:1 ratio
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Know the formula to calculate dB SPL (sound pressure level)
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20 log (output/reference)
Reference: 20 micropascals or 2x10^-5 Pa |
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What are the two types of interference?
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constructive interference and
destructive interference Note: When two sounds meet. |
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_______ occurs when on area of condensation encounters an area of rarefaction. The sound will equalize. Also, it results in a decrease in amplitude and may result in a complete cancellation of sound.
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destructive interference
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_________ occurs when one are of condensation meets another area of condensation, rarefaction meets rarefaction. Results in an increase in amplitude up to a doubling of amplitude.
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constructive interference
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_______ places where sound is occuring.
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sound fields
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________ is close to sound source, w/in 1 meter, typically no reflections, no inverse square law.
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near field
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_______ greater than 1 meter from sound source, inverse square law applies, with free field & diffuse field.
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far field
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_______ no reflected surfase for sound to encounter, such as an anechoic chamber.
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free field (type of far field)
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_______ reflections present, interference occurs.
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diffuse field (type of far field)
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________ is an object's natural frequency of vibration; the frequency that produces the max vibration.
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resonance
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Each object has only one resonant frequency. T or F
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True
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___________ is object's best frequency, longest vibe time, minimal energy to cause it to vibrate, friction/damping has the least effect, and only 1 resonant frequency.
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natural resonant frequency
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Max amp will occur when the freqency of vibration of the driving object is equal to the resonant frequency of the receiving object (i.e. two tuning forks). T or F
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True
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The bigger (increase) the mass, the lower (decrease) of the resonant frequency. T or F
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True
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If the density of the propagating medium is uniform, opposition to the flow of sound energy (propagation) does not exist, the acoustic impedance is zero. T or F
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True
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If the density of the propagating medium does change, then impedance to sound propagation does exist. T or F
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True
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What is the impedance of air?
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5.0 x 10^2 rayls
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What is the impedance of water?
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1.5 x 10^6 rayls
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Low frequency diffract better than high frequency sounds due to their larger wavelengths. T or F
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True
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A ____ can cause sound to diffract if it is small with respect to the wavelength sound.
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hole
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Waves are blocked or reflected if sound wavelength is less than the size of the object. T or F
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True
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The amplitude of frequencies that the filter will not pass has a term called ________.
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attenuated
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____ is a special type of resonator.
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filter
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The frequencies to which the filter vibrates are the ones the filter will pass; amplitude of these frequences is unaffected. T or F
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True
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4 passes. Frequencies. Certain point.
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high-pass filter, low-pass filter, band-pass filter, band-reject filter.
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_______ is frequency values above, below, or between which the filter passes the sines without reducing their amplitudes; also defined as the frequency where the pwoer falls to half its peak value.
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cuff-off frequency
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_______ is the 3 dB below the peak amplitude, aka the the 3 dB-down point.
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half-power point
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_______ is the frequency difference bw the half power or the 3 dB cut-off frequencies.
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bandwidth
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_______ is the middle frequency of band-pass and band-reject filters.
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center frequency
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______ _____ the slope of the line depicting how rapidly the amplitude is reduced (dB/octave; is the amount of attenuation given to the amplitude of the sines beyond the cut-off frequency is expressed in dB's per octave of frequency.
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rejection rate
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_______ is the difference bw maximum and minimum amplitudes.
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dynamic range
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Frequency. Values. 3 dB. Frequency difference. Middle frequency. Slope amplitudes. Minimum amplitudes are key words for ______ ___ _ ____.
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characteristics of a filter
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damped or dampening?
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damped
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______ is a physical measurement of _______ or ______.
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amplitude, intensity, or pressure.
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_______ __ _____ is similar to a domino-like transfer of energy from air molecule to air molecule.
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transmission of sound
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_______ the medium is compressed: therefore, a local region of higher-than-normal density exists (as tines on a tuning fork go out, for example).
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compression (or condensation)
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compression = high pressure
rarefaction = low pressure, T or F? |
True
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_____ the medium is stretched; therefore, a local region of lower-than-normal density exists (as tines go in).
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rarefaction
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How fast does sound propagate? The speed of sound depends on the composition and density of the medium (ex: the density of air varies w/ temp/elevation/humidity, etc). T or F?
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True
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What the waveform can tell us about vibration: _____, _____, _____, ____, ____.
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frequency, period, amplitude, phase, and duration.
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Circular or polar notation: 360 degrees in a circle, is characteristic of phase.
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Char. of phase.
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What point are we in a circle? Find the answer by comparing it to a phase. T or F?
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True.
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Complex aperiodic sound, even though amplitude varies randomly, an average amplitude measure can be calculated. T or F?
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True
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The relationship between intensity and pressure: the power of a sound is proportional to the pressure multiplied by itself, that is, to the square of the pressure. (Ex: if the pressure is doubled, the power becomes four times as great). T or F
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True
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