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124 Cards in this Set
- Front
- Back
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Describe the psychological terms of sound.
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loudness and pitch
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Describe the physical terms of sound.
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intensity and frequency
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Define sound (3 basic elements).
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Sound is a "disturbance" in a "medium" caused by a "vibrating body".
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Explain "Pressure Wave".
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*Sound behaves as a "wave" in air as it travels and exerts "pressure" on objects (the tempanic membrane).
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What type of medium is required for the vibration of sound?
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An elastic medium (for us it is gaseous air).
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What are the 3 types of elastic mediums?
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gas, liquid, solid
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True of False: Vibratory Motion and Wave Motion are the same thing.
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False. A vibrating body produces waves when it is immersed in an elastic medium. The waves that are generated travel through the medium.
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Define Vibratory Motion.
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Motion flowing back and forth along a path restoring force that increases with displacement, always directed toward position of rest.
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What does "periodic" describe?
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Vibratory motion occurring in equal time intervals.
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What must sound have in order to be heard?
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Vibration with certain frequency and intensity.
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What are the 5 measurable characteristics of vibratory motion?
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1. Displacement
2. Amplitude 3. Frequency (f) 4. Period (T) 5. Phase |
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Explain displacement.
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The distance from equilibrium to the position of the vibrating body at that instant.
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Explain amplitude (also known as peak amplitude).
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The distance between peaks (+) and valleys (-). The greater the distance, the greater the amplitude.
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Explain frequency (f) and how it is measured.
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the time (seconds/Hz) it takes to complete 1 vibration or cycle.
*CPS= cycles per second or Hz ex:100 CPS= 100 Hz |
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What is the range of human hearing frequency, as measured in Hz?
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20 Hz to 20,000 Hz
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Define period (T).
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*time required to generate one cycle/vibration
*measured in fractions of a second or milliseconds |
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What is the relationship b/t frequency and period?
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They are reciprocals. If a body makes 60 vibrations per sec, frequency is 60 Hz. Since each vibration occurs in 1/60 sec, its period is 1/60.
*T=1/f and f=1/T T=Time in seconds f=Frequency in Hz |
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Explain phase and how it is measured.
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*describes vibratory as well as wave motion and describes relationship b/t 2 or more vibrations
*measured in degrees of an angle (circular) |
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What do we call the point in the phase cycle at which the object begins to vibrate?
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Starting Phase
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What is Simple Harmonic (or sinusoidal) Motion (SHM) ?
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*simplest form of vibratory motion
*restoring force is always proportional to displacement (Hooke's Law) *constant exchange of kinetic and potential energies. |
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All forms of matter will transmit (longitudinal or transverse) waves.
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Longitudinal because any matter that responds to compression and has elasticity (which all matter has) will transmit longitudinal waves.
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How are longitudinal and transverse waves different?
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The direction of movement in a longitudinal wave is PARALLEL to the direction of propagation and is PERPENDICULAR in a transverse wave.
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What is used to represent the velocity (speed) of air particle movement as well as the extent and frequency of movement?
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Sine Curve which also represents compression and rarefaction.
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When does cancellation of two tones occur?
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When they are 180 degrees out (same frequency and amplitude but opposite phase)
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What are the 3 types of vibration?
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free, forced, and maintained
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Give an example of "free vibration" and explain.
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A tuning fork is one example of free vibration because it has energy imparted and continues to vibrate periodically until energy has dissipated.
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It is characteristic of a free vibrator to vibrate at its own __________?
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Natural Frequency
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A free vibrator absorbing energy best when the energy source has a frequency rate exactly the same as the vibrator is called ___________?
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Resonance (or transference of energy)
ex: a tuning fork absorbs energy from another tuning fork (both having the same natural frequency) and begins to vibrate on its own. |
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Vibratory or sound energy is imparted to a structure OTHER THAN its own natural frequency is an example of __________?
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Forced Vibration
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When a struck tuning fork is placed on a table and the table vibrates, energy is transferred but inefficiently. When the fork is removed from the table, the vibrating ceases almost instantly. This is an example of ______?
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Damping-when a displaced body returns to its position of equilibrium without passing through it.
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A vibrator that overcomes any damping and is permitted to maintain a constant amplitude of vibration is known as ___________?
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Maintained Vibration
ex: child pumping on a swing or a weight-driven pendulum of a clock (it continues to vibrate at the same frequency for a while) |
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The distance between any two points that represent 360 degrees phase change is 1 _______________?
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Wavelength
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The velocity with which sound waves travel through air is about __________ per second at room temperature.
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1,130 ft.
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Wavelength is determined by what formula? How is it measured?
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wavelength (Greek lambda symbol)=v/f
wavelength= velocity in ft. per sec/frequency in Hz or f=v/wavelength *Distance measured in feet b/t identical points on two adjacent waves. |
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Low frequency sounds have relatively _______ wave length and high frequency sounds have relatively _______ wave length.
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long; short
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What is the wavelength of a 113 Hz tone?
A 1,130 Hz tone? An 11,300 Hz tone? |
1,130/113= 10 ft
1,130/1,130= 1 ft 1,130/11,300= 0.1 ft *wavelength=v/f (whereas v=1,130 ft always) |
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Sound is a transfer of _______ from one location to another, not a transfer of __________.
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energy; matter
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Sound is considered ______ if we hear the ___________.
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audible; vibration
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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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Resistant external force on an object is known as _____________.
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inertia
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If something comes back to its original form it is known to have the property of ________?
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elasticity
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Even with no specific frequency of vibration being imparted to the system during the initiation of motion, the system vibrating at one specific frequency is known as ________?
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Free Vibration (vibrating BEST at a specific frequency)
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A free vibrator will absorb sound best when one object causes another object to vibrate, and the energy source has the same __________ as the vibrator.
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frequency
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When resistant forces come upon a freely vibrating object and over time the object ceases to vibrate ________ has occurred.
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damping
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If just enough energy is supplied continuously to the vibrator and it makes up for the loss of energy through mechanical resistance the result is a ___________.
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forced vibration condition (object will continue to vibrate under forced vibration as opposed to free vibration)
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With forced vibration it is possible to maintain a constant _________ of vibration over time.
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amplitude
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In a sound wave, molecules will separate themselves _______ when at rest, but they will _______ when acted upon by a vibrating object and ______ as the vibrating object moves away.
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equally; compress; spread out (rarefaction)
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If air pressure is at zero atmospheric pressure, then greater than atmospheric pressure is (+) ________ and less than atmospheric pressure is (-)___________ thus creating ___________?
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compression; rarefaction; sound waves
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The train car is an example of ________ where the tendency of matter at rest is to remain at rest and the tendency of matter in motion is to remain in motion.
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inertia
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Sound medium must have _______ or molecules and be __________ or have elasticity.
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mass; compressible
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What are the two ways sound differs from other vibrating motion?
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*3D in free air
*propagated as longitudinal in direction of propagation |
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Waves in water are an example of _________ waves. Waves in air are an example of ___________ waves.
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Transverse; Longitudinal
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People in line at a ticket booth where one person at one end knocks into the person next to them and so on is an example of ____________ waves.
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Longitudinal because the individual people do not move great distances, and neither do compressed molecules.
*movement of each air molecule is local and different than the velocity where the wave travels through the medium |
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If you shout to a person 1/2 block away and the energy you created (not the molecules) moves through the air & sets the molecules 1/2 block away next to the person's ear into motion __________ just occurred.
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Propagation
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_______ is the speed of the energy traveling from my lips to your ears & it us usually predictable.
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Velocity (speed of sound or C)
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The speed of sound (C) is dependent on medium ___________ and medium _________.
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density; temperature
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At sea level & 20 degrees C or 68 degrees F, speed of sound is ____M/sec or _____ ft/sec.
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344; 1,130 (or 1,125)
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Remember, it is the _________ that moves, NOT the _________ when it comes to propagation.
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disturbance; medium (gaseous air-STAYS HOME!)
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AGAIN, the _______ is transferred from one location to the next, the _________ is not transferred.
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energy; medium
ex: people in line, ripples in water |
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Period (T) of 10,000 Hz tone =?
Period (T) of 1,000 Hz tone =? Period (T) of 125 Hz tone =? *frequency=1/T so find the f of each of the above. |
T=1/10,000= 0.0001 sec
T=1/1,000= 0.001 sec T=1/125= 0.008 sec *f= 1/T (0.0001)=10,000 Hz *f=1/T (0.001)= 1,000 Hz *f=1/T (0.008)= 125 Hz |
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Wavelength of lower frequency will be ________ than wavelength of higher frequencies.
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longer
*wavelength = speed (C)/ f or 1130/f |
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What is the velocity of sound in air?
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1,130 ft/sec and it does not change
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If wavelength=C/f
(1,130/500)= 2.26 ft then f=C/wavelength (1,130/2.26)= ______ Hz and C= f x wavelength (500 x 2.26)= _______ft/sec |
500; 1,130
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A ________ is created when two or more sine waves are combined. Most of our environment is made up of these waves.
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Complex wave
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The simplest sound wave is a ______?
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sine wave
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A pure tone when added to another pure tone becomes more ______.
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complex
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A sound _________ is a way of illustrating by using lines and showing content of a complete ______ wave.
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spectrum; complex
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Phase angle of zero combined with a phase angle of 180 degrees results in the _________ of __________.
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absence of sound
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The ear (is/ is not) sensitive to phase and the sound will be (same/different).
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is not; same
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Who stated that pure tones can be combined to create complex tones and complex tones can be broken down into pure tones?
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Joseph Fourier
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If a complex wave is irregular in flow but repeats itself identically from Lt to Rt, it would appear to be _________.
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Periodic
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A means by which we illustrate discret events or individual components of a whole is called a ___________?
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spectrum
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On a line spectrum the ___________ and __________ distribution is represented on the Abscissa and Ordinate lines.
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frequency and intensity
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The ____________ measures frequency along the __________ line.
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Abscissa; horizontal
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The __________ measures intensity along the ___________ line.
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Ordinate; vertical
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List the characteristics of a Periodic Sound.
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*wave form repeats regularly
*components are harmonics of some fundamental frequency *components are mathematically related *will have a musical quality |
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The lowest frequency of vibration, and also known as the first harmonic, is called the ________ __________.
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fundamental frequency
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Any single frequency component (part) of a complex tone in acoustics is a ______.
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Partial
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__________ are whole number multiples of a fundamental frequency.
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Harmonics
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The _____ harmonic is the fundamental frequency. The second harmonic is ___ x's the fundamental freq (fo x 2). The _____ harmonic is 3 x's the fundamental frequency, etc.
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first; 2; third
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The fundamental frequency is not an overtone, therefore the first overtone is the ________ harmonic (fo x 2). The second overtone, which is 3 x's the fo would be the ________ harmonic, etc.
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Second; third
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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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In a complex wave, frequency (increases, decreases) in Hz with harmonics.
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increases
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In a harmonic series, we _____ to the fundamental frequency. In an octave series each successive octave is ______ by ____.
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add (125, 250, 375, 500 Hz, etc); multiplied by 2(125, 250, 500, 1000 Hz, etc.)
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When a waveform repeats itself at regular intervals as it moves from Lt to Rt it is considered ________.
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periodic
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A line spectrum of a periodic waveform has (less, more) energy in decibels (intensity) as it moves from fundamental freq. to 1st harmonic, to 2nd harmonic, etc.
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less
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A complex wave that is non-repetitive in waveform an its components are not harmonically related is known as _______ ___________.
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aperiodic sound
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Aperiodic sound can have components at all ___________ rather than at multiples of a fundamental frequency. It is typically referred to as "________".
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frequencies; noisy
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_____ usually defines something that is not desired, aperiodic, and has great irregularity in the wave form. Some, however, can be used for our enjoyment.
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Noise
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Aperiodic complex sound is neither ________ or related in a _________ way.
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predictable; mathmatical
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When all frequencies are represented at equal intensities resulting in a flat spectrum, it is called ______ ______.
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White noise
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White noise term was borrowed from the idea of ________ _______ as when all the colors of the ______ _____ are brought together resulting in the color white.
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light spectrum; light spectrum
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White noise which filters certain frequencies to to yield equal intensity per octave is called _____ ______.
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pink noise
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With pink noise, ________ gradually decreases by 3 dB with each octave as _________ increases .
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intensity; frequency
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We can take white noise and with filtering shape it such that it replicates the long time average _____ _____.
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speech spectrum
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When white noise is used to filter all other noise so that only the center frequency is presented, these are known as a ______ ______ of frequencies.
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Narrow band
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Center frequencies are typically _______ frequencies and are excellent for masking ______ ______.
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audiometric; pure tones
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An _______ is used to test the range of frequencies a person can hear.
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audiogram
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If you wanted to prohibit a person from hearing 1000 Hz of pure tone you would put a 1000 Hz ____ ______ of noise in that same ear and they would not be able to hear the pure tone.
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narrow band
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In a _____ _____ noise the successively higher harmonics decrease in intensity and sounds like a humming sound. It is not aperiodic and consists of a fund. freq. and series of harmonics.
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Saw Tooth
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Sound does exert ______ on objects it encounters. As sound _________ increases and decreases so does our perception of ________ or _________.
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pressure; pressure; loudness; intensity
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The sound pressure ratio of most intense sound possible (tolerated by human ear) and the least intense sound pressure (detected by human ear) is ________________;_____.
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100,000,000,000,000:1 or using base 10 we could write 10 w/ exponent 14:1
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The problem of large ratio scales can be solved by converting ______ scales to ________ through the use of ______.
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ratio; interval; logarithms
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In an interval scale, intervals between successive values are ______ or ______.
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equal; linear
ex: 1+0=1, 1+1=2, 1+2=3, etc -move by values of 1 |
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In a ______ scale, each product is twice the value of its predecessor.
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ratio
ex: 2x0=0, 2x1=1, 2x2=4, 2x4=8, 2x8=16, etc. if numerical unit is 10 then 10x's the value: 10x0=0, 10x1=10, 10x10=100, 10x100=1000, etc |
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The _______ of a number is simply the power by which 10 must be raised in order to equal a given value. Ex: 10 must be raised to the second power to equal 100.
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logarithm
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The differential information of a base 10 number is with the _________ values or __________, not in the bases themselves.
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exponential; logarithm
*without exponents there are no differential differences to the bases |
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We can convert a _____ scale into a _______ scale simply by removing the bases.
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ratio;interval
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For our convenience, the _______ or ratio scale has been converted to a ________ scale.
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logarithmic; interval
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Don't forget the large logarithmic sound pressure values as you move along the interval scale.
*Give an example and explain. |
7 to 8 is only an interval of 1 on a scale, but 10 to 7th power to 10 to 8th power is a very significant move. 10 to the 3rd power to 10 to the 4th power would be much less significant.
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Sound pressure ______ as it moves logarithmically.
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increases
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Each interval unit in sound intensity is called a ____, named after ______ _____ ________.
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Bel; Alexander Graham Bell
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The range of human hearing as to intensity is a range of ______ Bels or ______ dB.
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14; 140
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Bels divided into tenths are called ___?
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decibels or 1 Bel = 10 decibels (dB)
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True or False: Ratios are dimensional quantities.
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False. They are dimensionless, we have no idea how large they are.
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What are the two expressions for sound intensity?
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dB IL=intensity 10 x Log I / I
O R ef point dB SPL= pressure 20 x Log P / P O utput R |
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Why is 10 times the logarithm for intensity and 20 times the logarithm for pressure?
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Intensity is proportional to P squared.
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Because dB is calculated from the ratio of two sound pressures and ratios are dimensionless, the dB scale is ______ and not absolute.
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relative
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________ = force/ unit area
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Pressure
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A unit of force is a __________.
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Newton (N)
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One Newton (N)is a force that will accelerate one kg mass, a distance of one meter, per second (time). Explain using the eraser/table example.
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Eraser=1 kg (mass)
Table=1 meter (distance) Finger on end of eraser uses force to move it across the table in 1 sec (time) |
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The unit of sound pressure is called a __________ named after _______ _________, the French scientist/ philosopher known for his work with ________ __________.
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Pascal (Pa); Blaise Pascal; Barometric Pressure
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One Pascal is equal to one Newton per ______ _______.
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Square meter (& 1 unit of sound pressure = 1 N)
1 Pa= 1 N/M squared |
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The smallest sound pressure variation required to produce a just audible sound o healthy young ears is approximately __________?
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0.00002 Pa (20 millionth)
*It was decided that 0 dB SPL = 20 millionth of Pa. *a millionth is a.k.a a micro-pascal |
