Acoustics

Question 1

What are the two prevailing theories of pitch perception?

Question 2

What is Interaural Time Difference (ITD)?

Question 3

What is Interaural Level Difference (ILD)?

Question 4

What is a limitation of gap detection tasks when using pure tone stimuli?

Question 5

What is dip listening?

Question 6

How does dip listening help our perception of speech signals?

Question 7

Which frequencies is the auditory system most sensitive to small changes and why might this be?

Question 8

What is critical bandwidth?

Question 9

How will you know when you’ve reached critical bandwidth when testing for masked detection threshold?

Question 10

What happens to bandpass filters in the presence of hearing loss?

Question 11

How do bandpass filters alter loudness and pitch perception?

Question 12

What are MAP/MAF functions?

Question 13

Which testing procedure yielded better thresholds for detection?

Question 14

What is the difference between dB SL, dB HL, dB SPL and IL?

Question 15

Why does increasing stimulus bandwidth improve detection thresholds for amplitude modulation detection?

Question 16

How can I alter the stimulus to improve signal detection in a forward masking condition?

Question 17

What would reduce the reverberation time of a room in order to make a speaker easier to understand?

Question 18

What is dynamic range of a system?

Question 19

How might dynamic range be helpful when fitting a hearing aid on a patient?

Question 20

In open/closed system, where is the area of highest and lowest pressure?

Question 21

A doubling of intensity results in a ______ dB increase, while a double of pressure results in a _______ dB increase.

Question 22

If the fundamental frequency of a system is 674 Hz, what is the frequency of the 4th overtone? What is the second octave?

Answer 22

3375 Hz = 675 Hz
2700 Hz = 2nd octave

Question 23

What is the level of a signal relative to the background interfering signal?

Answer 23

Signal to Noise Ratio (SNR)

Question 24

What is a favorable SNR value?

Answer 24

Positive SNR is when the signal exceeds the noise level; this is favorable since listener will have more clarity and better speech discrimination

Question 25

What is unfavorable SNR?

Answer 25

Negative SNR is when the noise level exceeds the signal level; this is unfavorable since the listener won't be able to clearly hear a speaker in a noisy environment

Question 26

If the peak to peak amplitude of a sine wave is 34, what is the rms amplitude?

Question 27

What happens to a signal during on/off transient? How do we avoid this?

Question 28

If a system is in resonance, what force(s) are acting in opposition to its movement?

Question 29

What is the opposite of impedance? What is its unit of measure?

Answer 29

Admittance Unit: mho

Question 30

What is the difference between a broadly tuned system and narrowly tuned system?

Question 31

As a stimulus duration decreases, frequency specificity ___________. Why is this important to know?

Question 32

What technique is used to assess what frequency information is contained within a complex signal?

Answer 32

Fourier Analysis

Question 33

What is the formula for frequency of a signal?

Answer 33

F = 1 / T T, period

Question 34

Calculate the relative amplitude of the 5th harmonic of a sawtooth wave

Answer 34

Fo = 200 Hz 200 x 5 = 1000 Hz, 5th harmonic

Question 35

What is the derived physical quantity that defines the time-rate change in velocity?

Answer 35

Acceleration

Question 36

Describe a low-frequency filter

Answer 36

Only low frequencies may pass; attenuates higher frequencies at a certain cutoff

Question 37

Describe high-frequency filter

Answer 37

Only high frequencies may pass; attenuates lower frequencies at a certain cutoff

Question 38

Describe a band pass filter

Answer 38

Only frequencies within a certain range may pass; attenuates frequencies above and below than the range limits

Question 39

Describe band reject filter

Answer 39

Frequencies outside of a certain range may pass; attenuates frequencies within the range

Question 40

What is the Doppler effect? Why does it occur?

Answer 40

Sudden perceived change in pitch of a signal as it moves away and toward the listener. As sound travels closer to the listener, the wave is also produced closer to the listener which results in higher pitch perception. As sound travels away from the listener, waves are produced farther away from the listener which results in lower pitch perception

Question 41

What is the unit for pressure?

Answer 41

pascal (Pa)