# Shared Flashcard Set

## Details

331 sound and hearing
midterm #1
76
Physics
02/15/2012

Term
 Simple Harmonic Motion
Definition
 SHM. certain type of periodic motion that occurs as a result of linear restoring force. Graphically looks like a cosine or sine depending on the starting position of the object t=0 on position (y) and time (x) axis. When a solid object moves in SHM it creates a frequency.
Term
 Linear restoring force
Definition
 Specific type of push or pull: 1. The force is in the opposite direction of the displacement from the equilibrium.2. the force is proportional to the distance from the equilibrium position
Term
 Amplitude
Definition
 the maximum distance from the equilibrium position. Graphically it is the distance from the top of the the curve to horizontal, or the bottom to horizantal.The amplitude can be the maximum value of any quantity of interst such as speed, (or velocity), change in pressure, change in density. always same on both sides of equilibrium. Cosine always starts at the top of a graph, (0). amplitude = A
Term
 Period
Definition
 The amount of time it takes for an object to move back and forth once. grahically it is the amount of time it takes in order to draw a repeating shape once. time it takes for one oscillation. unit = seconds. one oscillation is from one peak to next peak (distance). period = T. T= 1/F
Term
 Frequency
Definition
 the number of times an object oscillates i one second. unit = hertz (Hz). frequency = f. f=1/T
Term
 period vs. frequency
Definition
 when the period is lower that means the frequency is higher. and when the period is higher that means the frequency is lower.
Term
 W
Definition
 angular frequnecy   W=2∏F   alwasy start with W when graphing the shape of an oscillation
Term
 Shape of an oscillation (cosine)
Definition
 x(t)= Acos(Wt+Φ) (equation when wave is in SHM) t = time Φ = angle phase
Term
 time
Definition
 always x axis on a graph unit = t
Term
 Phase Angle
Definition
 An angle between 0 and 360 degrees that specifies a point in one cycle.   0 = beginning of cycle 90 = 1/4 from beginning 180 = 1/2 270 = 3/4 360 = same as 0 degrees   graphical equation = Sin(Wt)
Term
 Out of Phase
Definition
 180 degrees = half the period   cancels out sound waves   if two graphs are out of phase, they are the same shape and and everything, but flipped upside down.
Term
 In Phase
Definition
 2 quantities have the same period and frequncy and are not offset at all.   In phase means in sync waves.
Term
 Diffraction
Definition
 Process by which waves appear to bend around corners   Ie. someone facing the opposite direction and the abilit to still hear them is because of diffraction.
Term
 Polarization (transverse)
Definition
 transverse wave: the object of the wave is moving in a perindicular manner relative to the direction the wave is traveling.   the object is moving up and down along an x axis.   if polarized; the object moves in a particular direction in the plane.   the motion is ordered.   if unpolarized; moves in all directions and is the motion is random.
Term
 K
Definition
 constant vaue of  force that is pulling or pushing the object in motion.
Term
 Hookes Law
Definition
 F = -K(x) F = force W =(√K/m)
Term
 V
Definition
 Velocity   velocity as a function of time:   V(t) = -W2ASin(Wt + Φ)
Term
 Postion
Definition
 x(t)   position as a function of time:   x(t) = Acos(Wt + Φ)
Term
 acceleration
Definition
 (a) acceleration as a function of time:   a(t) = -W2Acos(Wt +Φ)
Term
 Transverse wave
Definition
 the material that carries the energy moves in a direction that is perpindicualr to to the energy itself.   particle speed = rate at which the energy goes up and down   Deep water waves, and light waves
Term
 Longitudinal wave
Definition
 the material that carries the energy is moving in a paralell direction compared to the direction of the energy itself.   sound waves.   molecules move from mouth to ear in a longitudinal manner.
Term
 Speed
Definition
 speed of anything = distance/time   v = x/t   f= λ/T
Term
 Speed of a wave
Definition
 speed of a wave     V= λf
Term
 Speed of sound
Definition
 v(sound) = (331+.6Tc ) unit = meters/second if the air is hotter the wave moves faster, and vice versa if the air is colder.   (25 m/s = 60 mph)
Term
 speedof sound in air
Definition
 345 m/s   use this assumption when speed and temperature are not given
Term
 celcius conversion
Definition
 Tc = 5/9(Tf - 32)
Term
 largest and smallest wavelengths that can be heard?
Definition
 345 m/s  20 Hz   = 17.5 meters = maximum wavelength   345 m/s 20,000 Hz   = 17.25 mm = 1.725 cm = minimum   (10 mm = 1 cm)
Term
 Huyugens principle (H's principle)
Definition
 all parts of a wave act as sources of spherical waves in three dimensions   ie: old waves make new waves like the ripple effect on water.
Term
 Priciple of superposition
Definition
 to find the total amplitude of two or more waves, just add the individual amplitudes of each wave
Term
 Inverse Square Law
Definition
 if a wave spreads out in all directions (three dimensions) then its intensity will decrease in proportion to the square of the distance from its source.   ie: three dimension 5x the distance = intensity will decrease 25 times.   two dimensions the intensity will decrease in proportion to the distance   ie: 5x the distance = intensity will decrease by 5
Term
 Reflection
Definition
 reflection occurs when a wave bounces off of a boundry between two differnt materials.   Th angle of the incident = the angle of reflection   25 degree angle of incident = 25 degree angle of reflection
Term
 Refraction
Definition
 occurs when the wave changes direction due to crossing through a boundry betwen two different materials.   wave bends   light traveling through glass changes direction
Term
 dispersion
Definition
 when a wave begins to disperse through space and spread as it moves further and further.   the lower the frequency the higher the dispersion, and vice versa for higher frequency
Term
 interference
Definition
 waves don't necessarily interfere, they combine in two different manners having different effects
Term
 spatial interference
Definition
 when two or more waves with the same frequency fromm different sources combine at some point   when waves interfere spatially the resulting two extreemes are constructive and destructive
Term
 constructive spatial interference
Definition
 percents out of 100%   constructive = in phase   ie: 37% constructive/63% destructive   used for audio mixng
Term
 destructive
Definition
 destructive spatial interference = out of phase   used for kareoke
Term
 constructive and destructive
Definition
 refers to the pressure change   constructive:  two waves with same graphical patterns cmbine   results in increase in pressure change   destructive: two waves with opposite graphical pattersn combine and cancel eachother out.   pressure change is (wave one - wave two)
Term
 Time like interference
Definition
 occurs when two or more waves with different frequnecies from same source combine in some point in space.
Term
 Beats (time like interference)
Definition
 when waves interfere in time   two waves, different frequencies, same source, combine some point in space, two things could happen:   1. the frequency heard will be the average of the  two frequencies:   f(average frequency of combined wave) = f1 + f2 2 2. the combined wave will get louder and softer at a rate equal to the absolute value of the of the difference between the two frequencies.   f(beat) = absolute (f1-f2)   (in tune frequency = 0)
Term
 The doppler effect
Definition
 if the source of the sound wave and/or the listener are moving with respect to the material carrying the sound wave, then the frequency heard by the listener will be different  than the frequency emitted by the source   most commonly used to calculate speed of listener, or source.   effects the wavelength as well   f0 = V +/- Vo V +/- Vs   do not compare the source ot the observer, compare it to the material carrying the wave.
Term
 doppler effect: approaching
Definition
 if the source and listener are moving toward eachother the frequency heard will be higher than the frequency emitted by the source.
Term
 doppler effect: receeding
Definition
 if the source and and listener are moving away from eachother the frequency heard will be less than the source frequency.
Term
 doppler effect: equations for different possibilities
Definition
 4 possibilities relative to material   1. S approaching, O approaching = + numerator/- denominator   2. S approaching, O receeding = - numerator/ - denominator   3. S receeding, O receeding = - numerator/+ denoinator   4. S receeding, O approaching = + numerator/+denominator
Term
 Doppler effect: material carrying wave is moving
Definition
 ie: air = wind speed   ie: source approaching moving 20 m/s observer receeding moving 10 m/s material moving 5 m/s toward  = source actually moving at 15 m/s observer actually moving 5 m/s material actually moving 0 m/s
Term
 Shock waves
Definition
 shock waves occur when object is moving faster than the speed of sound   not periodic
Term
 Sonic Boom
Definition
 created when multiple shock waves created at various times are combined to form one single shock wave of a large amplitude
Term
 ultrasonics
Definition
 sound waves that have a frequncy greater than 20,000 Hz   Sonar, medical imaging, material analysis, ultrasonic cleaning, dow whistles, echolocation, cavitation research
Term
 Infrasonics
Definition
 sound waves with frequency less than 20 Hz   cruisers with loud subwoofers, earthquakes, thunder, underground imaging (palentology, archeology, geology, natural resources), motion sickness.
Term
 traveling waves
Definition
 one wave that travels in only one direction
Term
 standing wave
Definition
 result of two identical waves traveling in opposite directions that undergo constructive spatial interference   often results from one wave that undergoes reflection at one or two places.
Term
 Mersennes law
Definition
 f = fundamental frequency L = langth of string F = force of tension apllied to the string W = mass per unit length of string (density x area)   f = (1/2L)√(F/W)
Term
 Mersennes law: length, tension, mass per unit length
Definition
 1. length; longer strings produce lower notes; violin, viola, cello, bass   2. tension: greater tension creates higher notes; tuning a guitar or piano (if increased from 5lbs to 10lbs, tension dos not double, watch for √)   3.  mass per unit langth; thicker create lower notes; strings on a piano   (if you make a string 2x as thick, the area increase 4x, which = 1/2 the frequency)
Term
 Mersennes law; fundamental frequency
Definition
 equal to teh speed of the wave divided by twice the length of the string   (only applies to string/wire)   speed of a wave = √(F/W)
Term
 string instruments: modes of excitation
Definition
 bowing; violin, viola, cello, etc. uses friiction, string stretches creating triangular displacment.  Linear restoring force.     plucking; guitar, harp, harpschord, etc. spherical displacement   striking; piano, hammer dulcimer, etc.
Term
 wind instruments; open at one end and closed at other (closed)
Definition
 the air at the closed end cannot vibrate, and the air at the open end can.   creates a longitudal wave, molecules move towards open end of tube.   air at the open end always antinode (maximum amplitude)   clarinet, and bass clarinet
Term
 wind instruments (closed): equations for wave length
Definition
 general equation = λ = (4L)/N   N = harmonic number, and is always odd
Term
 wind instruments: open at both ends
Definition
 the air at bothe ends can vibrate.   string instruments work the same way   air molecules are moving like an accordian from the center of the tube; they move outward then inward after half a period.   base on node placement
Term
 open wind instrument equation
Definition
 fN = (Nv)/(2L)   ie; 1 node λ = 2L 2 nodes λ  = L 3 nodes λ  = (2/3)L
Term
 standing wave relationship to nodes and harmonics
Definition
 1 standing wave = 1 node/1 harmonic 2 = 3 node/3 harmonic 3 = 5 node/5 harmonic
Term
 closed wind instruments and overtones
Definition
 1st node/harmonic = fundamental frequency 3rd node/harmonic= 1st overtone 5th = 2nd overtone 7th = 3rd overtone
Term
 wind instrument cylindrical open
Definition
 piccolos, flutes, and bass flutes recorders
Term
 Wind instruments closed cylindrical
Definition
 clarinets and bass clarinets
Term
 wind instrument concical (not covered)
Definition
 soprnao, alto, tenor, bass sax oboes, and bassoons all brass instruments   acts like cylindrical open
Term
 edge tones
Definition
 organ pipes, flutes   mode of excitation
Term
 reed tones
Definition
 single or double   mode of excitation   single; clarinets and saxaphone double oboes and bassons
Term
 lip tones
Definition
 trumpet, trumbone, tuba
Term
 turbulence
Definition
 sinnging tubes or whirling tubes
Term
 how to change a note (frequency)- (wind instruments)
Definition
 change the effective length side holes; flute, clarinet, saxophone valves; trumpet, tuba, french horn slide; trombone, penny whistle
Term
 change the harmonic number (wind instruments)
Definition
 register keys; supresses fundamental to produce the next possible harmonic   over blowing; adds more energy to the air allowing for higher harmonics
Term
 Frequency of sound wave
Definition
 related to the tone, note or pitch that is heard   larger freq. = higher notes, and vice versa for low freq.
Term
 amplitude sound wave
Definition
 related to the loudness that is heard   large amp = louder
Term
 damping SHM
Definition
 the process in which energy of a SHM oscillator is transformed into some other kind of energy
Term
 Damped harmonic motion DHM
Definition
 decrease in amplitude
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