Acoustics
Define resistance.
Define reactance.
Resistance- opposition to motion
Reactance- how we apply energy to a system
Define rise time. Define fall time.
Rise- when the tone is initiated till peak amplitude.
fall- from peak amplitude to tone termination
True or False: Temporal Integration is a phenomena where absolute threshold improves with increasing stimulation duration (up to 200-300 MS).
True or False: Schroeder-Phase stimuli have their phases adjusted to produce a flat envelope, negative maskers are more effective then positive ones.
True x2
Temporal processing can be described as
a. detect signal in noise
b. quickly responds to stimulus
c. perception sounds which vary overtime
d. perception of sounds that vary in frequency
C
True or False: We measure pitch of a complex tone by having subjects adjust the frequency of a pure tone until it matches the pitch of the complex.
True or False: Both place and temporal theories can support pitch perception for the harmonic complex, including the phenomenon of missing fundamental.
True.
False.
Define SNR.
True or False: A positive SNR is more desired then a negative SNR
SNR is the relationship between the desired signal and the background noise present.
True.
Which of the following are log rules?
a. LogAB= LogA+LogB
b. LogA/B=LogA-LogB
c. LogA^B=B*LogA
d. LogA-B=LogB+LogA
A-C
Select all that apply to Overshoot:
a. reduced by cochlear hearing loss or aspirin intake
b. active mechanism influenced by efferent system
c. greatest effect for a broadband masker at moderate level and signal of relatively high frequency
d. another term for backward masking or excitation patterns
A, B & C
Match: forward, simultaneous, backward masking
a. probe and masker overlap in time
b. probe followed by masker
c. masker is followed by probe
a. simultaneous
b. backward
c. forward
True or False: Loudness declines because of adaptation over a period of minutes. Effect greatest at high frequencies and low levels, for steady tones. Modulation of tone reduces or eliminates the effect.
True or False: Fatigue can be measured as the degree of temporary threshold shift and can last for a period of minutes to days. It is greater at half-octave frequency above the frequency of intense stimulation. Greatest immediately after exposure. Permanent damage occurs because TTS affects synapses of nerve.
True.
True.
Fill in the blank: low, high
______ damping system will vibrate for a long time while _______ will die out quickly.
Low, High.
What are the three possible issues with an FFT?
How would you solve each problem?
Aliasing: high hz sound masquerades as low hz
fix with low pass filter
Leakage: energy spreads from narrow to broad range
Fix with adding a window to smooth it out
Picket Fencing: peaks merge with other energy and become undetectable
fix by increasing number of points in the graph
Select all that apply to excitation patterns:
a. represent output from Lat. Lemniscus and Inf. Colliculus
b. provide summary of what masking would occur in absence of off-freq listen
c. developed to show effect of single narrowband masker across range hz
d. derived by calculating outputs as function of frequency
e. model of masking patterns based on data from noise-notched filter experiments
f. discovered by Fechner
B, C & E
Select all that apply to forward masking:
a. decays over time
b. masker and probe at same frequency
c. increases with duration
d. caused by ringing of BM at low frequencies
e. function of signal delay
f. growth is gradual at longer delays
All of the above.
Match: Amplitude, Frequency, Phase
a. degree at which a signal starts
b. rate a sinusoid repeats
c. pressure or intensity of a sound
a. phase
b. frequency
c. amplitude
Whats the difference between a free field and a diffuse field?
free is no obstacles in way of sound waves
diffuse is equal flow of energy in all directions, there are possible in way of the sound waves
What are the three types of filters? Which frequencies are cut off with each?
Define attenuation rate.
Low pass, cuts off highs. High pass, cuts off lows. Bandpass, has range that goes in and comes out.
Attenuation rate is the dB per octave roll off.
Match: Increment, Amplitude Modulation, Intensity
a. detect intensity increment in longer duration sinusoid
b. detects the presence of sinusoidal modulation
c. present two intervals differing in intensity and ask listener to indicate the interval with a louder tone
a. increment
b. amplitude modulation
c. intensity
Choose the best definition for profile analysis:
a. modulation pattern similar for all active auditory filters can be detected
b. listeners compare temporal shape of signal to enhance signal to noise ratio of masker
c. compares outputs across filters to enhance detection, like CMR.
C
Consider “missing fundamental frequency” in pitch; normal listeners pitch of tone consisting of 300, 450. 600, 750 and 900 hertz pure tones will mostly correspond to the following frequency
a. 150
b. 900
c. 300
d. 100
a. 150
Difference between transverse waves and longitudinal waves.
transverse- moves up and down but not forward
longitudinal- moves in all planes
Describe the Hooke's Law.
Springs! Resting state until acted upon by outside force.
Select all that apply to masking level differences:
a. when tone or noise is presented in phase to two ears the image is heard at the center of the head
b. when waveform is inverted the image is more diffuse and is lateralized to both ears; more audible when tone lateralized and Nosie at center
c. only occurs at low frequencies
d. standard MLD task involves detection of low frequency tone in noise
e. MLDs defined as differences in amount of masking that occurs as function of IPD
All the above.
Choose examples of temporal processing tasks:
a. gap detection
b. sinusoid amplitude modulation detection
c. onset/offset asynchronous detection
d. discrimination of duration
e. loudness scaling
f. judgement of temporal order
g. gap duration discrimination
h. modulation detection
A, B, C, D, F, G, H
Define formants.
Define resonance.
Formant- peaks of acoustic energy in speech sounds.
Resonance- vocal tract enhances some frequency, inhibits others.