Acoustics Flashcards
What are the two prevailing theories of pitch perception?
What is Interaural Time Difference (ITD)?
What is Interaural Level Difference (ILD)?
What is a limitation of gap detection tasks when using pure tone stimuli?
What is dip listening?
How does dip listening help our perception of speech signals?
Which frequencies is the auditory system most sensitive to small changes and why might this be?
What is critical bandwidth?
How will you know when you’ve reached critical bandwidth when testing for masked detection threshold?
What happens to bandpass filters in the presence of hearing loss?
How do bandpass filters alter loudness and pitch perception?
What are MAP/MAF functions?
Which testing procedure yielded better thresholds for detection?
What is the difference between dB SL, dB HL, dB SPL and IL?
Why does increasing stimulus bandwidth improve detection thresholds for amplitude modulation detection?
How can I alter the stimulus to improve signal detection in a forward masking condition?
What would reduce the reverberation time of a room in order to make a speaker easier to understand?
What is dynamic range of a system?
How might dynamic range be helpful when fitting a hearing aid on a patient?
In open/closed system, where is the area of highest and lowest pressure?
A doubling of intensity results in a ______ dB increase, while a double of pressure results in a _______ dB increase.
If the fundamental frequency of a system is 674 Hz, what is the frequency of the 4th overtone? What is the second octave?
3375 Hz = 675 Hz
2700 Hz = 2nd octave
What is the level of a signal relative to the background interfering signal?
Signal to Noise Ratio (SNR)
What is a favorable SNR value?
Positive SNR is when the signal exceeds the noise level; this is favorable since listener will have more clarity and better speech discrimination
What is unfavorable SNR?
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
If the peak to peak amplitude of a sine wave is 34, what is the rms amplitude?
What happens to a signal during on/off transient? How do we avoid this?
If a system is in resonance, what force(s) are acting in opposition to its movement?
What is the opposite of impedance? What is its unit of measure?
Admittance
Unit: mho
What is the difference between a broadly tuned system and narrowly tuned system?
As a stimulus duration decreases, frequency specificity ___________. Why is this important to know?
What technique is used to assess what frequency information is contained within a complex signal?
Fourier Analysis
What is the formula for frequency of a signal?
F = 1 / T
T, period
Calculate the relative amplitude of the 5th harmonic of a sawtooth wave
Fo = 200 Hz
200 x 5 = 1000 Hz, 5th harmonic
What is the derived physical quantity that defines the time-rate change in velocity?
Acceleration
Describe a low-frequency filter
Only low frequencies may pass; attenuates higher frequencies at a certain cutoff
Describe high-frequency filter
Only high frequencies may pass; attenuates lower frequencies at a certain cutoff
Describe a band pass filter
Only frequencies within a certain range may pass; attenuates frequencies above and below than the range limits
Describe band reject filter
Frequencies outside of a certain range may pass; attenuates frequencies within the range
What is the Doppler effect? Why does it occur?
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
What is the unit for pressure?
pascal (Pa)
