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104 Cards in this Set
- Front
- Back
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When we say we hear, we usually mean we are ________ to the _______ in our environment.
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sensitive, sounds
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Sounds may be defined in what two types of terms?
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Psychological and Physical
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What are the psychological definitions of sound?
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Variation in loudness and pitch.
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What are the physical definitions of sound?
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Variation in intensity and frequency.
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Sound is a __________ in a _________ caused by a _________ body.
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disturbance, medium, vibrating
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Sound is a pressure ________ that consists of __________ of an _________ medium.
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wave, vibrations, elastic
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Name the three types of elastic mediums.
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gas, liquid, solid
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Sound is ________ which is capable of being ________.
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vibration, heard
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Sound is a transfer of _______ from one location to another.
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energy
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Any object with the properties of _________ and __________ may be set into vibration and therefore create ________.
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inertia, elasticity, sound
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If we hear the vibration, sound is ________.
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audible
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What is the movement of an object from one point in space to another point and usually back again to the original point?
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vibration
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The force on the object to make it moves defines ________.
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inertia.
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The ability of the object to return to a starting state after it is deformed or moved defines ___________.
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elasticity
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Almost every object has _______ and _______ and therefore almost every object can be set into ________.
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inertia, elasticity, vibration
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This occurs occurs when a mechanical system is set off with an initial input and then allowed to vibrate freely. Examples of this type of vibration are pulling a child back on a swing and then letting go or hitting a tuning fork and letting it ring.
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free vibration
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Even though no specific frequency of vibration is imparted to the system during the initiation of the motion, the system vibrates at one specific frequency. What is this called?
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natural frequency
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When does a free vibrator absorb sound energy best?
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When the energy source has a frequency which is the same as the vibrator.
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What are the resisting forces upon a freely vibrating object?
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damping
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What is created when just enough energy is supplied continuously to the vibrator to make up for the loss of energy through mechanical resistance?
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forced vibration
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With forced vibration, it is possible to maintain a constant _________ __ _______.
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amplitude of vibration
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When sound waves are at rest, they are separated by ________ _______.
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equal distance
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Vibration causes a sequence of __________ and _________.
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compression, rearefaction
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What are waves of greater than atmospheric pressure?
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Compression (condensation)
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What are waves of less than atmospheric pressure?
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Rarefaction
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A sound source must have what two things in order to vibrate and produce sound?
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elasticity and inertia
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If there is no _______ material or ________ medium, there is no production or propogation of sound.
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elastic, elastic
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A sound medium (air), must have _____ and be __________ (have elasticity).
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mass, compressible
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Sound waves in free are are ________ _________.
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three dimensional
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Sound in air is propagated as what?
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a longitudinal wave - i.e. air molecules lie in the direction of propogation
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What are waves on water?
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Transverse waves
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Movement of each air molecule is _______.
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local
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What moves when you yell?
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The energy that has been created - NOT the molecules coming from your mouth.
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The speed of sound (C) is dependent on what two things?
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medium density, medium temperature
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At sea level (20 degrees C/68 degrees F), the speed of sound is
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344 m/s or 1130 ft/sec
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REMEMBER: it is the _________ that moves, NOT the ________.
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disturbance, medium (air -a gas)
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Simple sine waves have what three parameters?
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amplitude, frequency, starting phase
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What is the height of the compressions and rarefactions?
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amplitude
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What is frequency?
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how often one cycle is completed (per second)
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What are hertz?
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cycles per second/frequency
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What is the range of human hearing for frequency (Hz)?
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20 Hz to 20,000 Hz
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What is the time required to generate one cycle?
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Period (T)
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How is period (T) measured?
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fractions of a second or milliseconds
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What is the equation for T?
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T = 1/f
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What is the equation for f?
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f = 1/T
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Low frequency sounds have a relatively _____ period.
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long
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High frequency sounds have a relatively _____ period.
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short
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What is the distance in feet between identical points on two adjacent waves?
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wavelength
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What is the equation for wavelength?
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wavelength = C/f (C=speed of sound, 1130)
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Low frequency sounds have a relatively ______ wavelength.
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long
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High frequency sounds have a relatively ______ wavelength.
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short
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What is the point in the cycle at which the object begins to vibrate?
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starting phase
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What occurs when two or more sine waves or pure tones are combined?
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a complex wave
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With complex waves, the exact same _____ may combine in different ways depending on the ______ relationships of the ________ pure tones so that the resultant ______ form looks different.
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tones, phase, component, wave
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The ear is not sensitive to _______ and the sound will be the same to it.
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phase
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Joseph Fourier noted that any complex sound can be broken down into a series of _________ ______ _____.
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component pure tones
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When a wave form repeats its pattern, what is it called?
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periodic
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What is a means of illustrating the individual components of a whole?
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spectrum
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In a sound analysis, what usually shows discrete frequencies as parts of a larger acoustic event?
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line specturm
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Complex Waves - Periodic Sound Characteristics:
1. Regularly ________ waveform 2. Components are __________ of some fundamental frequencies 3. Components are thus, __________ related. 4. Will have somewhat of a ________ quality |
1. repeating
2. harmonics 3. mathematically 4. musical |
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What is the lowest component frequency of a complex wave?
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Fundamental Frequency / First harmonic
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_________ are whole number multiples of a fundamental frequency.
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Harmonics
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What is the first harmonic?
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fundamental frequency
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The second harmonic is the frequency which is ____ times the fundamental frequency.
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two
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What is the first overtone?
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The frequency which is two times the fundamental frequency (second harmonic). fo X 2
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If 125 Hz is the fundamental frequency, then ____ Hz would be the first overtone and _____ Hz would be the second overtone.
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250, 375
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Which kind of series takes the first number and adds itself over and over
Ex: 125, 250, 375, 500, etc. |
harmonic series
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What kind of series has each successive number and multiplies it by two?
Ex: 124, 250, 500, 1000, etc. |
octave series
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What is the horizontal coordinate on a sound spectrum called?
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abscissa
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What is the vertical coordinate on a sound spectrum called?
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ordinate
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A non-repetitive waveform is characteristic of what?
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Aperiodic Sound
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In aperiodic sound, components are not ________ _________.
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harmonically related.
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What can have components at all frequencies rather than only one at multiples of a fundamental frequency?
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aperiodic sound
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What typically has a noisy characteristic or quality?
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aperiodic sound
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What is sound with great irregularity in the wave form?
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noise
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What is unwanted, usually aperiodic sound?
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noise
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What represents all frequencies at equal intensities?
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white noise
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What kind of noise is characterized by a flat spectrum?
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white noise
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What is the amount of energy among the component frequencies of a vibratory phenomena?
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spectrum
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What is white noise that has been shaped to yield equal intensity per octave?
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pink noise
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In pink noise, because each successive octave has _____ the number of frequencies as the one just before it, the spectrum level must decrease _____ per octave in order that the intensity per octave be equivalent.
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twice, 3 dB
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What is white noise which is shaped such that it approximates the shape of the long time average speech spectrum?
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speech spectrum
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Narrow band noise is ______ ______ which has been band-pass filtered such that only a ________ _______ of frequencies surrounding some center of frequency is presented.
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white noise, narrow band
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With narrow band frequencies, what are typically audiometric frequencies?
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center frequencies
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What is excellent for masking pure tones?
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narrow band noise
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What sounds rather like a humming sound?
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saw tooth noise
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In what kind of noise do the successively higher harmonics decrease in intensity?
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saw tooth noise
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For audiometric purposes, what kind of noise is essentially useless?
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saw tooth noise
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Which kind of noise is actually not an aperiodic sound?
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saw tooth noise
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What fundamental frequency does saw tooth noise consist of?
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60 Hz
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What kind of noise is good for masking speech?
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white noise
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What is the sound pressure ratio of the most intense sound possible/tolerated by the human ear?
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sound intensity
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What is the least intense sound pressure detected by the ear?
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sound intensity
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What kind of scales has successive values that are equal or linear?
Ex: 1+0=1 1+1=2 2+1=3 |
interval scales
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What kind of scales have each product being twice the value of its predecessor?
Ex: 2X0=0 2X1=2 2X2=4 |
ratio scales
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What is the ratio of sound intensity?
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10 to the 14th:1
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The differential information of sound intensity is not in the _____ but with the __________.
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base, logarithm
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The range of hearing as to intensity is a range of
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14 Bels (140 dB)
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Pressure is defined as
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force/unit area
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A unit of force is a ________.
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Newton (N)
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One Newton is a force that will accelerate what?
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One kilogram of mass a distance of one meter per seconds squared.
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The unit of sound pressure is called what?
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pascal (Pa)
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What is the equation for Pa?
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one Newton per square meter
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0 dB SPL equals how many Pa?
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20
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