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93 Cards in this Set

  • Front
  • Back
what is the physical definition of sound
series of vibrations of molecules in a medium
what can constitute a medium
gas, liguid, solid
sounds are waves of tine flucuation in ____ ________ that ________ ( ) from the source
air pressure, propagate (radiate)
our ear drums ______ when those presssure waves reach our ears
the auditory system converts the pressure waves to _____ ______ that the brain processes, interprets and classifies
neural impulses
air occupies space and there is a relationship between volume and ________. which is known as what law
air pressure...boyles law
a vibrating tuning fork causes localized _____ _____ changes by displacement of molecules next to the tines which push against their neighbors and so on. setting up a wave of energy of small increases and decreases in ambient pressure that propagates through space
air pressure
the cycle of increased pressure is
compression phase
the cycle of decreased pressure is
rarefaction phase
how does sound occur
an object is vibrated by a force.
what two things does an object need in order to vibrate
elasticity and inertia.
what is inertia
force must be acted on by an object to make it move
what is elasticity
ability of an object to return to initial position after movment.
how does a pendulum illustrate the need for inertia and elasticity
without elasticity the pedulum would just continue out to one side into infinity. without inertia, the pendulum would not continue once straight up and down.
what is the point of dispacement
when it swings out to first sidee
what is max displacement
as far as it will go
what is positive max displacement
first side it swings to
what is neg max displacement
second side it swings to
how many frequencies are there in a sine wave...what type of tone is a sine wave
pure tone. 1 frequency
what does a sine wave have the same trajectory as
a circle
what is the degree at the point of rest
if a tree falls in teh forst and there is noone there to hear it does it make a sound? what are the two sides of the answer
1. depends if you think sound needs an ear to receive it
2. you can say the molecules moved so there is sound
do we often hear sine waves in our lives
no, most sounds in our lives are complex
what is vibratory motion
movement that occurs when as object is set into motion by a force
what is the simplest pattern of vib. motion called
sinusoidal or sine wave
describe the displacement of the vib. object with a sine wave
continuous, regular, back and forth displacement
when does displacement occur
when an object is acted on by a force
what is the displacement pattern of a sine wave called
simple harmonic motion
in sine wave, displacement around rest is _______
the vibrating pattern of a given sine wave repeats itself into -______
what constitues a cycle for a sine wave
1 transition of motion. from 0-360 degrees
what are the five ways to describe simple harmonic motion
1. frequency
2. period
3. amplitude
4. phase
5. wave length
what is the definition of frequency? what is the units? what is the psychological corelate
# of cycles completed in a second. hertz (Hz). pitch
describe the relationship between pitch and frequency. and the reason
they are related but are not a 1 to 1 relationship. reason: frequency is measured but pitch is just in your head- no way to measure
what is the definition of period? what is it measured in?
amount of time it takes to complete 1 cycle. units time (T). usually measured in seconds or milliseconds
definition of amplitude.
strength of vibration of molecules. amount of vibratory displacemnt; distance molecules are displaced from object @ rest
psychological correlate
4 ways to measure amplitude
1. instantaneous amplitude
2. peak amplitude
3. peak to peak amplitude
4. rms amplitude
instantaneous amplitude varies with
what is inst. ampl
measure of amplitude at any point in time across the wave. time dependent
peak amplitude
amount of amplitude at points of max displacement
peak to peak amplitude
from 1 point of max displacement to another. add the two together. take absolute valeu of neg. max. displ.
rms amplitude
root mean square. average. purpose: want the average instantaneous amplitude of a sine wave. take the amplitude values and square them. then get the average of squared numbers. then take square root.
what is the easy way to find rms
peak amplitued x 0.707
what kind of waves are used in hearing tests
sine waves
in hearing tests, what is the purpose of rms?
rms ampl. is used to compare sine waves and says which one is louder.
point in the cycle where the object begins to vibratef
what is phase measured in
instantaneous phase
the measurement of phase at any point along the wave.
the distance between two consequtive positive peaks or two consequtive negative peaks on a sine wave.
what are the two things that wavelength is effected by
frequency and speed of sound in air
what is the constant (speed of sound in air)
344 meteres/second
does wavelength increase or decrease as frequency increases and why
increases. frequency = cycles per second. will be much closer together as frequency increases. shorter wave lenght
what is intensity a measure of
of sound strength
what is the purpose of log rhthms
condences log #'s. scientific short hand.
intensity = (one word)
unit for intensity
decibels (dB)
is decibel a ratio or an absolute value
ratio is what
decibel is (one word)
4 types of decibel
1. dBSPL- sound pressure level
2. dBIL - intensity level
3. dBSL- sensation level
4. dBHL- hearing level "clinical decibel"
dBSPL- two things u need
1. measured pressure- will be given
2. reference pressure- will be memorized
reference pressure
what are the two reference pressures and how do you know which to use
1. Pr= 20 mPa
2. Pr= 2 x 10^-5 0.0002 Pa

pick which to used depending on the unit of hte measured pressure.
does 0 dBSPL mean no sound
no. dBSPL is a ratio. measured pressure/reference pressure. means the reference pressure and measured pressure are the same thing. there is very soft sound at 0 dBSPL.

100 dBSPL is not 100x louder than 0 dBSPL.
how many dBSPL for a jet engine? for leaves on a tree?
120, 15
what is dBSL
decibel sensation level.
what is a sensation
a sound in comparison to another. since they are being compared must have like values.
what is the dBSL for 30 dBSPL and 75 dBSPL
45 dBSL. tone 2 is 45 dBSL compared to tone 1.
what is dBHL
clinical decibel. antime a hearing test is given- it is dBHL. hearing level is always talked about in dBHL
what is a complex wave
any wave that is not a sine wave but is composed of a series of sine waves that can differ in amplitude, frequency and phase
2 types of complex waves
1. complex periodic wave
2. complex aperiodic wave
what does complex mean about frequency
more than one frequency
periodic means what
it repeats itself
complex periodic wave.
several sinusoids summed- not randomly chosen.
wave has ________ pattern
added sines are ____________ related
they are ______ _______ nultiples of one another
whole number
300-> 450-> 600
series starts with the sine of the _______ frequency called the________ aka________
lowest. fundamental frequency. first harmonic
complex aperiodic wave
no relationship between sine waves. no repeatable pattern.
example of sound with aperiodic wave? what is the behavior of hte instantaneous amplitude
noise. instantaneous amplitude varies over time in a random manner. no dicernible pitch.
examples of aperiodic wave
sounds like steam hissing. /s/, /f/, /h/. snow on a tv.
resonant freqency
when a vibrating object is set into free vibration, it will vibrate at a frequency determined by its physical properties including mass, elasticity, and tension
the natural frequency of a ________, ________, __________ are examples of resonance
tuning fork, pendulum, ear canal
what is the resonant frequency when something is under forced vibration
you're doing something to it. a drum when u hit it. the resonance frequency is that at which the least amount of energy imput is required.
can an enclosed volume of air resonate why why not?
yes. because air is anelastic medium, it can be alternately compressed and expanded
special examples of resonators that remove some frequencies while allowing others to remain. cut off frequency.
4 kinds of filters
1. high pass
2. low pass
3. band pass
4. band reject
high pass filter
removes frequencies below the cut off. passes the high
low pass filter
removes frequnecies above the cut off. passes the lows
band pass filter
has 2 cut off frequencies. everything between teh two cut off gets passed.
band reject
2 cut off frequencies. what is inside gets filtered