exam 1 lectures 1-5 Flashcards
(98 cards)
1
Q
what is audibilty?
A
detecting sound
2
Q
what is intelligibility?
A
understanding sound
3
Q
approx what percent of americans report hearing loss?
A
17%
4
Q
percent of hearing loss in ages 45-64
A
18%
5
Q
percent of hearing loss in ages 65-74
A
30%
6
Q
percent of hearing loss in ages 75+
A
47%
7
Q
only ? of 5 people who could benefit from a hearing aid actually wear one
A
1
8
Q
- in 1000 US births result in a child with hearing loss (most common birth defect)
A
3
9
Q
– in 1000 US children have educationally significant hearing loss
A
83
10
Q
– percent of US babies are now screened within one month of birth
A
95%
11
Q
sound waves are..
A
ACOUSTIC
12
Q
vibrations are..
A
MECHANICAL
13
Q
neural signals are…
A
BIO-ELECTRICAL
14
Q
TWO uses for signals and systems analysis in speech and hearing
A
- helps to understand the technological signals and systems that we use in our work to study speech and hearing issues
- helps to understand the physiological systems we are studying
15
Q
sound
A
the VIBRATION (motion) of an object that results in the OSCILLATION of a MEDIUM through which energy propagates
16
Q
Sound needs a —— to carry it
A
MEDIUM
17
Q
some objects
A
tuning fork, drum head, violin string, piano string, vocal folds
18
Q
some media (sound goes propagates through)
A
air, water, floor and walls, stretched rope, etc
19
Q
a disturbance that produces a sound is called a
A
SOUND SOURCE
20
Q
what you need to create sound:
A
sound source, elastic medium
21
Q
elasticity
A
the ability of mass to return to its natural shape (the ability to resist changing shape)
22
Q
compressions
A
high pressure areas
23
Q
troughs
A
rarefactions, low pressure areas
24
Q
condensation
A
high pressure, high density
25
rarefaction
low pressure, low density
26
wave propagation
air particles OSCILLATE back and forth around their equilibrium position. the pressure wave travels through the medium
27
although sound waves are LONGITUDINAL, we represent them as
TRANSVERSE waves, amplitude/pressure vs. time
28
mechanical signal
variation in DISPLACEMENT over time
29
acoustical signal
variation in AIR PRESSURE with time
30
electrical signal
variation in VOLTAGE with time
31
amplitdue is related to
LOUDNESS
32
frequency is related to
PITCH
33
starting phase is related to
LOCALIZATION
34
RMS amplitude for SINE WAVES ONLY (otherwise have to square root the mean of the square of the wave)
0.707*A (A=peak amplitude)
35
PERIOD (cycle): T
measures in sec
one period is movement from equilibrium to maximum displacement in one direction, back to equilibrium, on to maximum displacement in the opposite direction, and then back to equilibrium
36
period is the time is take sto complete...
ONE CYCLE
37
cycle
extending rom any point ina wave to the next identical point (pattern)
38
Frequency
measured in Hz (cycles/second)
number of cycles (periods) PER unit of time
39
FREQUENCY and PERIOD are in a ---------- relationship (inversely proportional
RECIPROCAL
** watch for units
40
period --------- as frequency ---------
DECREASES, INCREASES
41
humans can hear sounds between -- and ----- Hz
20 AND 20,000
42
waveforms can be out-of-phase if they...
LEAD OR LAG
43
sound pressure
indicates how compressed or rarefied the particle are
FORCE per unit area
44
any object with ---- (INERTIA) and ---------- (STIFFNESS) can VIBRATE
mass, elasticity
45
inertia
mass
property that objects in motion or rest tend to stay in motion or rest (Newton's first law of motion)
46
elasticity
stiffness/spring
property of an object that tends to return to its resting state
47
sinusoidal oscillation results at a frequency determined by the ---- and --------- of oan object
mass, stiffness
48
any real object will NOT ------- forever (free) because it also has friction or -------
VIBRATE, DAMPING
49
--------- of motion is gradually diminished as energy is lost due to friction
AMPLITUDE
50
friction takes ---- energy and converts it into ----
AWAY, HEAT
51
air pressure
a function of the force exerted on a given area by the molecules of air
52
air pressures INCREASES when:
when density increases
53
density --------- when volume ---------
INCREASES, DECREASES
54
sound propagation is about alternating ------- in density OR pressure
CHANGES
55
in sound wave propagation, it is only the ---- that moves across space, not the molecules themselves
WAVE
56
all sound waves have the following properties:
FREQUENCY
WAVELENGTH
PROPAGATION
AMPLITUDE
57
the speed of propagation (speed of ------) is a function of the medium (also due to MASS and ELASTICITY)
SOUND
58
sound travels about 4.2 times ------ in water (1480 m/s) than in air (350 m/s)
FASTER
59
frequency, amplitude, and phase do --- change the speed of sound
NOT
60
the farther you are from a sound source, the ------ the intensity of the sound that reaches your ear
LOWER
61
for waves with an expanding area, the energy per area is ------ during propagation
REDUCED
62
sound intensity
indicates how much POWER is transferred from the sound source to the surrounding area
POWER per unit area
63
power is ----------- of area
INDEPENDENT
64
sound pressure (the amplitude of a sound wave) depends on the -------- from the sound source, which produces sound at a specific -----
DISTANCE
POWER
65
sound intensity is proportional to the ------ of sound pressure
SQUARE
66
doubling of PRESSUE (db)
+6 DB
67
halving of PRESSURE
minus 6 dB
68
factor of 10 increase in PRESSURE
+20 dB
69
factor of 10 INCREASE in PRESSURE
-20 dB
70
doubling of INTENSITY
+3 dB
71
halving of INTENSITY
-3 dB
72
factor of 10 INCREASE in INTENSITY
+10 dB
73
factor of 10 DECREASE in INTENSITY
-10 dB
74
used to describe the property by which sound passes around or is scattered by "small and medium" objects
diffraction
74
diffraction is ---- pronounced when the wavelength is LARGER than the size of the molecules
MORE
75
as waves diffract around an object, they leave a ----- ------ on the opposite side
SOUND SHADOW
76
sound shadows are more significant for ------- wavelengths, or ------- frequencies
SMALLER, HIGHER
77
is it the size of the object relative to the --------- that matters
WAVELENGTH
78
object > wavelength
high frequencies
little or no diffraction
79
object < wavelength
low frequencies
diffraction occurs
80
object~=wavelength
medium frequencies
81
when two traveling waves that are either BOTH positive or BOTH negative meet
ADD to create a GREATER pressure
constructive interference
82
when two traveling waves of different signs (positive and negative) meet
CANCEL to create a SMALLER pressure
destructive interference
83
when sounds are reflected from a boundary, a listener receives direct and reflected sounds
reverberation and echo
84
sound level within the room is a combination of:
direct field
diffuse field
85
direct field
original sound source
86
diffuse field
all the echoes in a room
87
room that have no echoes (expensive to design)
anechoic rooms
88
what is a way to characterize the acoustics of a room?
REVERBERATION TIME (RT)
89
the time it takes for the reflections from a sound source to be reduced by 60 dB
reverberation time
90
generated by the interaction of two sinewaves (a wave and its reflection) of equal amplitdue, traveling in opposite directions
standing wave
91
landmarks in standing wave
nodes
antinodes
92
our ears process sounds that are complex waves, ie waves that are composed of one of more frequency:
periodic sounds
transient sounds
noise
93
states that any complex wave can be understood as the sum of a set of sinuisodal waves
fourier's theorem
94
all higher frequencies in the series must be integer -------- of the fundamental frequency
MULTIPLES
95
altering the amplitude of one component affects...
waveform shape ONLY
96
if first fundamental is missing, what is NOT affected?
waveform periodicity
pitch
97
altering the PHASE of one componenet affects waveform...
SHAPE
