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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

vibrate


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

0


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 _______

symmetric


the vibrating pattern of a given sine wave repeats itself into ______

infinity


what constitues a cycle for a sine wave

1 transition of motion. from 0360 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

loudness


4 ways to measure amplitude

1. instantaneous amplitude
2. peak amplitude 3. peak to peak amplitude 4. rms amplitude 

instantaneous amplitude varies with

time


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.


phase

point in the cycle where the object begins to vibratef


what is phase measured in

degrees.


instantaneous phase

the measurement of phase at any point along the wave.


wavelength

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)

loudness


unit for intensity

decibels (dB)


is decibel a ratio or an absolute value

ratio


ratio is what

comparison


decibel is (one word)

pressure


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 

Pr=

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

predictable


added sines are ____________ related

harmonically


they are ______ _______ nultiples of one another

whole number


150>

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


filters

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
