Unit One

Question 1

In order to have sound what do you need to have?

Answer 1

A medium

Question 2

What is sound?

Answer 2

A disturbance of particles in a medium

Question 3

What is vibratory motion?

Answer 3

the back and forth motion of an object about its rest position

Question 4

What is another name for simple vibratory motion

Answer 4

simple harmonic motion (SHM)

Question 5

What is the equation for period?

Answer 5

Period = 1/frequency

Question 6

What is the equation for frequency?

Answer 6

Frequency = 1/period

Question 7

What does this formula mean?

Z = [R^2 + (Xm -Xs)^2]^1/2

Answer 7

Z = impedence

R= resistence

Xm = mass

Xs = stiffness

Question 8

What is occuring at these spots?

Answer 8

Nodes

Question 9

What is an antinode?

Answer 9

When there is constructive interference and waves are in phase sound occurs here

Antinodes have compression and rarefraction

Question 10

What is a node?

Answer 10

Where there is destructive interference and two standing waves meet in phase opposition. Sound does not occur here

Question 11

What is occuring at these spots?

Answer 11

antinodes

Question 12

What is compression?

Answer 12

areas of increased particle density (air pressure)

For hearing this moves the tympanic membrane inward

Question 13

What is rarefraction?

Answer 13

the equalizing aor decrease of particle density (air)

For hearing: this moves the tympanic membrane back out (to the original state) which equalizes pressure in the ear

Question 14

What is normal air pressure (at sea level)?

Answer 14

14.7 lb/in^2

or

100,000 Pa

Question 15

What is the equation of wavelength and what do the symbols mean?

Answer 15

wavelength (lamda) = c/frequency

lamda = wavelength

c = speed of sound in air

Question 16

What is the speed of sound in air?

Answer 16

1130 ft/second

344 meters/second

Question 17

What is the equation for natural resonant frequency (NRF)?

Answer 17

NRF = speed of sound/ (4L)

NRF = natural resonant frequency

L = length

Question 18

What are the four things that can happen when sound waves encounter obsticles in the environment?

Answer 18

Transmission

Reflection

Defraction

Absorbtion

Question 19

What is transmission?

Answer 19

When there is an impedence match (ie moving from air to air or water to water), the sound can travel thorugh the medium, the mediums are the same

Question 20

What is Reflection?

What is an example of relection?

Answer 20

There is an impedence mismatch and soudn doesnt travel through. The greater the impedence mismatch the greater the reflection.

Walls in a classroom

Question 21

What is defraction?

Answer 21

When the wave bends around the object. The object has to be 1/2 of the wavelength in order for it to defract.

Question 22

What is Absorbtion?

What is it called acoustically?

What is an example?

Answer 22

When sound is absorbed into an object and dissipated or changed into heat energy. The greater the surface area the greater teh absorbtion. Also the more pourous the material the more absorbtion

Acoustically this is called dampening

An anechoic chamber

Question 23

What is the equation of the inverse square law?

Answer 23

Inverse Square Law = Intensity = power/ 4pr^2

p = pressure

r = distance between you and the source

pressure = force/d^2

Question 24

When is this formula used?

Wavelength (lamda) = c/f

Answer 24

When you want to calculate the wavelength

Question 25

When is this equation used? c/4(L)

Answer 25

when finding the Natural Resonant Frequency (resoncance of a tube closed at one end) explains the influence of distance on the magnitude of speed as it travels from its source

Question 27

How would you explain 80 dB to a novice

Answer 27

it is 10,000 times the human threshold

Question 28

How would you describe -20 dB to a novice?

Answer 28

it is 100 times lower than the human threshold

Question 29

What is the logatrithms chart for decibles?

Answer 29

Question 30

What is the SPL equation?

Answer 30

SPL = 20 x Log₁₀ (P_o/ P_ref) SPL = sound pressure level which is the average level for a 1 KHz tone Po = observed soudn pressure Pref = 0.00002 Pa

Question 31

What is the Pref for the SPL equation?

Answer 31

0.00002 Pa

Question 32

What are the Sound Environments?

Answer 32

Sound Field Reberverent Field Anechoic Chamber Free Field

Question 33

What is a sound field? What is an example of a sound field?

Answer 33

there are better thresholds here example: when getting a hearing test

Question 34

What is a Reberverent Field?

Answer 34

where a sound is refected back (echos) and this tells you how big a room is, this is a normal field

Question 35

What is reverberation time?

Answer 35

the time it takes for sound to come back to you 1/1000 20x log (ratio) - 60 dB

Question 36

What is a free field:

Answer 36

Where nothing is reflected back at you Example of this is space

Question 37

What is an Anechoic Chamber

Answer 37

All soudns are absorbed here and turned to heat Anechoic Chamber called a tourchure chamber

Question 38

What do you need to have for a sound?

Answer 38

vibration (body cabable of vibrating) Medium (this is set into motion) an energy source There needs to be a disturbance of particles in a medium

Question 39

What do you experience or percieve in a sounds?

Answer 39

intensity (amplitude or loudness) frequency (pitch) phase (locaiton form Right to Left ear)

Question 40

What does Fourier's analysis measure?

Answer 40

Intensity Frequency Phase

Question 41

What does SPL stand for?

Answer 41

Sound Pressure Level the average threshold for a 1 KHz tone

Question 42

What is HL?

Answer 42

hearing level the average threshold for a specific audiometric tones audiologists use this

Question 43

What is SL?

Answer 43

sensation level particular threshold for any sound listener

Question 44

What is displayed by a speech spectrograph

Answer 44

Speech spectrograph is a slice by slice over time look measures: intensity (which is in terms of darkness) frequency (pitch) period

Question 45

What has node and antinodes in fixed spacial positions?

Answer 45

A standing wave

Question 46

What difference is there in the spectra of noise vs. tones?

Answer 46

Noise = random and peridoic, can't be repeated and diferent form one moment to the next Tones = pure tones and complex tones -\> they are periodic and can be repeated

Question 47

What type of graph is noise drawn on?

Answer 47

A continuous line spectrum

Question 48

What type of graph are tones drawn on?

Answer 48

Line Spectrum energy in discrete intregals