SHS 311 Exam 1 Questions and Answers
Question 1
what frequencies are most salient to the auditory system?
Correct Answer
2f1 - f2; must add up to 3
Question 2
high-pass filter
Correct Answer
- allows the high frequencies to pass (straight line on graph) and attenuates low
frequencies (where the slope is)
Question 3
what does the mass and spring represent in explaining a vibration?
Correct Answer
- mass = inertia - the resistance of an object to any change in its state of motion
- spring = elasticity - the restoring property of an object to its resting state
- inertia and elasticity are the two properties an object must have in order to vibrate
- a vibrating object will have the resting position (0, atmospheric pressure), a
minimum (-, downward) position, and a maximum (+, upward) position that it
oscillate against - move about an average mean value
- as sound waves travel through the air, they will create positive air pressure and
negative air pressure, oscillating/vibrating between the two
Page 1 of 29
,Question 4
reverberation time
Correct Answer
- the time it takes for reflected sound pressure to reach some defined proportion of
its original sound pressure
- how long does it take for the reflected sound pressure to, say, reach half of its
original pressure?
- short reverberation time = sound absorbed so pressure of wave decreases rapidly
- long reverberation time = pressure of sound wave gradually reduced (takes longer
for sound pressure wave to reduce in intensity)
- transmission loss dB = 10log(fraction transmitted)
- ex. 1/4 of the sound transmitted is transmitted through a material, so 10log(1/4) =
6.02 dB transmission loss
- reverberation depends on the volume of the room and the absorption at the
boundaries (volume/absorption) - sound proof booth minimizes reflections
Question 5
band reject filter
Correct Answer
- attenuates the amplitudes of all sinusoidal components with frequencies between
its cutoff frequencies
- the opposite of a band-pass filter
Question 6
frequency
Correct Answer
- the number of cycles per second, in Hertz (Hz)
- low frequency = completes less cycles per second
- high frequency = completes more cycles per second
- correlated to pitch - high frequencies are perceived as high, squeaky sounds, while
low frequencies are perceived as low, deep, bassy sounds
Page 2 of 29
, Question 7
static pressure
Correct Answer
- atmospheric pressure, where nothing is going on in the environment
Question 8
starting phase
Correct Answer
-θ
- the relative starting position of a sinusoid
- the starting position of a vibration relative to a reference starting position
- can be 0, 90, 180, or 270 degrees
- there is no perceptual correlate for starting phase, but we do know that it can
impact your ability to localize sound
Question 9
octave
Correct Answer
- a ratio of 2 in frequency
- used to describe the relative frequency relationships between two sounds
- it is essentially a doubling of frequency
- ex. how many octaves are for 800 Hz/100 Hz? - how many times do you need to
double
100 Hz to get 800 Hz?
100 x 2 = 200, 200 x 2 = 400, 400 x 2 = 800
you have doubled it 3 times, so there are 3 octaves
Question 10
nodes vs antinodes
Correct Answer
- nodes = areas of diminished vibration (no movement/vibration)
- antinodes = areas of enhanced vibration (max amount of movement)
Page 3 of 29
Question 1
what frequencies are most salient to the auditory system?
Correct Answer
2f1 - f2; must add up to 3
Question 2
high-pass filter
Correct Answer
- allows the high frequencies to pass (straight line on graph) and attenuates low
frequencies (where the slope is)
Question 3
what does the mass and spring represent in explaining a vibration?
Correct Answer
- mass = inertia - the resistance of an object to any change in its state of motion
- spring = elasticity - the restoring property of an object to its resting state
- inertia and elasticity are the two properties an object must have in order to vibrate
- a vibrating object will have the resting position (0, atmospheric pressure), a
minimum (-, downward) position, and a maximum (+, upward) position that it
oscillate against - move about an average mean value
- as sound waves travel through the air, they will create positive air pressure and
negative air pressure, oscillating/vibrating between the two
Page 1 of 29
,Question 4
reverberation time
Correct Answer
- the time it takes for reflected sound pressure to reach some defined proportion of
its original sound pressure
- how long does it take for the reflected sound pressure to, say, reach half of its
original pressure?
- short reverberation time = sound absorbed so pressure of wave decreases rapidly
- long reverberation time = pressure of sound wave gradually reduced (takes longer
for sound pressure wave to reduce in intensity)
- transmission loss dB = 10log(fraction transmitted)
- ex. 1/4 of the sound transmitted is transmitted through a material, so 10log(1/4) =
6.02 dB transmission loss
- reverberation depends on the volume of the room and the absorption at the
boundaries (volume/absorption) - sound proof booth minimizes reflections
Question 5
band reject filter
Correct Answer
- attenuates the amplitudes of all sinusoidal components with frequencies between
its cutoff frequencies
- the opposite of a band-pass filter
Question 6
frequency
Correct Answer
- the number of cycles per second, in Hertz (Hz)
- low frequency = completes less cycles per second
- high frequency = completes more cycles per second
- correlated to pitch - high frequencies are perceived as high, squeaky sounds, while
low frequencies are perceived as low, deep, bassy sounds
Page 2 of 29
, Question 7
static pressure
Correct Answer
- atmospheric pressure, where nothing is going on in the environment
Question 8
starting phase
Correct Answer
-θ
- the relative starting position of a sinusoid
- the starting position of a vibration relative to a reference starting position
- can be 0, 90, 180, or 270 degrees
- there is no perceptual correlate for starting phase, but we do know that it can
impact your ability to localize sound
Question 9
octave
Correct Answer
- a ratio of 2 in frequency
- used to describe the relative frequency relationships between two sounds
- it is essentially a doubling of frequency
- ex. how many octaves are for 800 Hz/100 Hz? - how many times do you need to
double
100 Hz to get 800 Hz?
100 x 2 = 200, 200 x 2 = 400, 400 x 2 = 800
you have doubled it 3 times, so there are 3 octaves
Question 10
nodes vs antinodes
Correct Answer
- nodes = areas of diminished vibration (no movement/vibration)
- antinodes = areas of enhanced vibration (max amount of movement)
Page 3 of 29
