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SLHS 302 Final Study Guide

Terms in this set (67)

Cochlear hearing loss affects...
Both audibility and speech intelligibility
What type of signal(s) does the ear deal with?
Acoustical, Mechanical, and Electrical
Variation in pressure...
Acoustical
Variation in position..
Mechanical
Variation in voltage...
Electrical
Maximum positive displacement of waveform
Peak amplitude
Time varying displacement measure
Instantaneous amplitude
Max positive displacement + max negative displacement
Peak-to-peak amplitude
0.707 x Peak Amplitude for sinusoids
Root-mean-squared amplitude
A sin wave has a period of 2 ms. It's frequency is...
500 Hz. Freq=1/period.
A hummingbird falls it's wings 3,060 times in a minute. What is the frequency in flaps/second?
51 flaps/sec. 3060 flaps/1 min x 1 min/60 sec.
A student sleeping in class snores 42 times in 3 minutes. What is the frequency of snoring in snores per second (sn/s)?
0.23 sn/sec. 42 snores/3 min x 1 min/60 sec.
One sinusoid (tone 1) has a frequency twice that of another (tone 2). Given that the period of tone 2 is 1/4 s, what is the frequency of tone 1?
8 Hz. 1/.25 =4. 4 x 2 = 8.
What determines the speed of a sound wave?
The sound medium
What determines the frequency of a sound wave?
The sound source
T/F? Condensation is when molecules are pulled apart, where density has deceased and the pressure is lower.
False
T/F? Decibels are relative, not an absolute, measurement
True
T/F? Wavelength is longer in water than in air
True
T/F? An object's oscillation frequency is lower in water than in air
False
T/F? Pressure is proportional to the square root of intensity
True
What is the difference between the period and the wavelength of a sound wave?
Wavelength: Amount of distance covered by a single period of wave, measured in meters. Period: Time it takes to complete one cycle, measured in seconds.
Explain the concepts of condensation and rarefaction in terms of sound propagation created from a vibrating object
Condensation: density of molecules compressed. High pressure. Rarefaction: Density of molecules spread out. Low pressure. Ears pick up difference in pressure, transmits to brain, & interpreted as speech
Explain the effect of damping on an oscillating object in terms of amplitude and frequency
Damping will decrease the motion of the object over time due to friction, mass, and elasticity. It reduced energy through friction. It affects amplitude because it will decrease over time. Frequency can only be changed by the sound source.
Explain qualitatively why sound intensity decreases as you move further away from a spherical sound source
Intensify decreases as you move further away because the energy of a sound wave is spread out over a larger area as distance increases
When does constructive interference occur? When does destructive interference occur?
Constructive interference: 2 points of condensation/rarefaction occur together resulting in areas of greater condensation/rarefaction. Destructive interference: 2 points of condensation/rarefaction overlap & cancel to create smaller pressure
What is a sound field without any reflections called? Is this common?
Anechoic. Not common
A researcher wants to use a SAM tone with a 500 Hz carrier frequency, a 100 Hz modulation frequency, and an amplitude of 8V at full modulation. What are the frequencies of the upper and lower side bands for this SAM tone? What would be the amplitude of each side band?
Upper: fc + fm. 500 + 100 = 600 Hz. Lower fc - fm. 500 - 100 = 400 Hz
What is the difference between a direct and diffuse field within a room?
Direct field: sound attributed to source with no reflections. Diffuse field: sound pressure level is uniform and reflected sound dominates
When expressed in decibels, sound level decreases by ___ dB for each factor of four increase in the distance from the sound source to the point of measurement.
12
Long sound wavelength
Object is "invisible"
Medium sound frequency
Diffraction around object edges (partial sound shadow)
High sound frequency
Complete sound shadow (i.e., object like a brick wall)
T/F? The Fourier Transform is used to convert from the time to the frequency domain
True
T/F? In-phase addition of two identical 65 dB SPL sounds
sources creates a higher dB SPL than the addition of two independent 65 dB SPL sound sources
True
What is the reverberation time (RT) of a typical anechoic room?
0.0 sec
Describe how interaural time differences are created, and why they are most prevalent at lower frequencies.
ILDs are created by the time interval, between when a sound enters the other ear. Most prominent at low frequencies because short wavelengths of high frequency make phase difference ambiguous and not able to be used like they can be for low frequency with their longer wavelength.
Describe the three mechanisms by which the middle ear amplifies pressure, and provide some quantitative sense for which of the three is the most significant
Area transformer, buckling action of the tympanic membrane, lever action of the ossicles. The most important is the area transformer because it prevents impedance
What two factors contribute to the 60-dB hearing loss that someone would experience if they lost their ossicles (e.g., with a severe cholesteatoma?)
Loss of lever action and area transformer because there is no stapes footplate
Describe in detail (i.e., the sequence of events) why your ears pop when you are flying and coming in for a landing (i.e., descending).
There is pressure buildup because the inside pressure does not equal the outside pressure. The eustatian tube cannot work fast enough to open and close which equals pressure
What are the three primary roles of the outer ear?
Cues for sound localization, amplify sound pressure, and protect the ear canal and middle ear
Which scala is connected to the stapes through the oval window?
Scala vestibuli
Which scala is bordered by Reissner's membrane, the organ of Corti, and the stria vasularis?
Scala media
If the human cochlea is 35 mm long, and all octaves of frequencies are equally spaced along the basilar membrane length (i.e., 20 to 40, 40 to 80,...), then how many mm of basilar-membrane distance is represented by each octave?
3.5 mm/octave. 35/10 = 35
Describe what is meant by the cochlea having a tonotopic representation. How does this relate to the cochlear traveling wave and resonant places along the basilar membrane?
Cells responsive to different frequencies are found in different places of the cochlea. Traveling wave = wave of displacement on Basilar Membrane. Travels apically, amplitude of vibration depend on intensity of sound
Since octaves are equally spaced along the basilar membrane, which corresponds to a longer distance on basilar membrane
All are equal distance
Which impedance factor varies along the basilar membrane and is the primary determinant of how resonant frequency changes along the length of the cochlea?
Stiffness
Which hair cell type is closer to the modiolus
Inner hair cells (IHC)
A particular stimulus causes three places of maximal displacement of basilar-membrane motion. What is most likely true about the stimulus?
It's a complex sound, with three frequency components
Choose which cochlear structure is primarily responsible for the following inner ear potentials:
Resting potential: Stria vascularis
Summanting potential: Inner hair cells
Cochlear microphonic: Outer hair cells
Action potential: Auditory nerve fibers
Which hair cells display motile responses? What protein facilitates that fast motile response?
Outer hair cells. Prestin
Which hair cells release neurotransmitter to send the majority of afferent information to the auditory nerve?
Inner hair cells
Describe two important differences between afferent and efferent auditory nerve fibers.
Afferent: Peripheral to central. Ascends to brain
Efferent: Central to peripheral. Exits the brain.
What is the main hypothesized function of efferent auditory nerve fibers
Central to peripheral, olivary complex to organ of corti
Which is not an example of an acoustically driven otoacoustic emission
Spontaneous otoacoustic emissions
Which is not a significant step in the transduction from stapes motion to action-potential generation in auditory- nerve fibers?
Hair cell is hyperpolarized when potassium ions (K+) flow in
Define neural saturation
Sound level neuron cannot increase firing rate further
Discuss two issues (one rate-based and one temporal- based) that limit the encoding of sound frequency.
Rate based: limited at high sound levels because it is harder to define the "best" frequency due to rate saturation
Temporal based: limited at high frequencies. Doesn't fire at every cycle due to the refractory period
Define "phase locking".
Ability of neurons to synchronize firing to a particular phase of a stimulus. Neuron will most likely fire at peaks of stimulus
Match the event with the order of occurrence.
First event: Action potential
Second event: Absolute refractory period
Third event: Relative refractory period
Match the AN-fiber threshold range and spontaneous-rate (SR) group.
Low-SR: High threshold
Medium-SR: medium threshold
High-SR: Low threshold
Is sound intensity likely to be encoded by a single auditory-nerve fiber?
No
For which neural code is tonotopicity most important?
Place code
Which of these frequencies is the highest for which the temporal pattern of a sound is still well represented in the spike-timing patterns
2000 Hz (Because diminishes 4-8 kHz. Need less than 4000 Hz)
Which landmark along the auditory pathway is the first point where binaural processing occurs?
The superior olivary complex (SOC)
Describe the landmarks that are represented by each wave of the auditory brainstem response (ABR).
Wave I: Auditory nerve
Wave II: Cochlear nucleus
Wave III: SOC
Wave IV: Lateral Lemnicus
Wave V: Inferior Colliculus
Considering the way sound frequency is coded in auditory nerve fibers, why might perceptual frequency discrimination get so much worse above 2 kHz?
There needs to be a larger difference between frequencies with higher frequencies. Phase locking also diminishes at about 2 kHz.
Which part of the auditory system primarily limits the frequency range of hearing?
Middle ear
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