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Final Exam SLHS 302

Terms in this set (64)

Cochlear Hearing Loss affects:
a. Audibility
b. Speech Intelligibility
c. Both Audibility and Speech Intelligibility
d. Neither Audibility or Speech Intelligibility
Both Audibility and Speech Intelligibility
What type of signal(s) does the ear deal with:
Acoustical;
B. Mechanical;
C. Electrical;
D. None of the above;
E. All of the above (i.e., A, B, and C)
E. All of the above (i.e., A, B, and C)
Match each description with the type of signal (0.5pts) acoustical, electrical, mechanical
Variation in pressure <--->
Variation in position <--->
Variation in voltage <--->
pressure: acoustical
position: mechanical
voltage: electrical
what is peak amplitude and instantaneous amplitude
peak: maximum positive displacement of waveform

instantaneous: time varying displacement measure
A sin wave has a period of 2 ms. It's frequency is:
2 Hz
5 Hz
500 Hz
200 Hz
500 kHz
500 Hz
A hummingbird flaps its wings 3,060 times in a minute. What is the frequency in flaps/second?
51 flaps / sec
A student sleeping in class snores 42 times in 3 minutes. What is the frequency of snoring in snores per second (sn/s)?
.23 sn/s
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
What determines the speed of a sound wave?
a. The sound source
b. The sound medium
c. Both the source and the medium
d. Neither the source and the medium
b the sound medium
What determines the frequency of a sound wave?
a. The sound source
b. The sound medium
c. Both the source and the medium
d. Neither the source and the medium
a. the sound source
True or False: Condensation is when molecules are pulled apart, where density has decreased and the pressure is lowered.
false
True or False: Decibels are a relative, not an absolute, measurement.
true
True or False: Wavelength is longer in water than in air.
true
True or False: An object's oscillation frequency is lower in water than in air.
false
True or False: Pressure is proportional to the square root of intensity
true
What is the difference between the period and the wavelength of a sound wave?
Period is time is takes for waveform to complete cycle (sec)
Wavelength is distance (m)
Explain the concepts of condensation and rarefaction in terms of sound propagation created from a vibrating object.
Condensation high density high pressure created by pushing condensing molecules

Rarefaction low density low pressure leaving rarefied air
Explain the effect of damping on an oscillating object in terms of amplitude and frequency.
The damping decreases motion over time or decreases the amplitude of an oscillating object as the friction strips away the energy.

Frequency det by mass stiffness and does not impact frequency
Explain qualitatively why sound intensity decreases as you move further away from a spherical sound source.
Spherical wave outward covers larger area farther distance from source and wave energy is fixed therefore intensity area reduced
When does constructive interference occur? When does destructive interference occur?
Construction interference occurs when there are two waves that are both positive or both negative overlaps, or come together to create a greater pressure when added together.

Destructive interference occurs when there is a negative and a positive wave overlapping and cancels one another out.
Explain diffraction and how it depends on object size.
Diffraction is how waves bend or change direction of propagation when they run into an edge of an obstacle or object.

small object, waves pass through the object and there is no bending or change in direction of the wave.

large object, the sound waves are diffracted back towards the sound source.

medium sized objects, diffraction creates a sound shadow behind the object through which the waves create a varying signal to noise ratio.
What is a sound field without any reflections called? Is this common?
A sound field without any reflections is called anechoic; this is not common because it is hard to find a place with no reflections and with total absorption.
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 sidebands for this SAM tone? What would be the amplitude of each side band?
The amplitude of each sideband is 4V because the side band amplitude is equal to ½ carrier amplitude for full modulation. The frequency of the upper sideband is 500 Hz + 100Hz = 600 Hz. The frequency of the lower sideband is 500 Hz - 100 Hz = 400 Hz.
What is the difference between a direct and diffuse field within a room?
direct field is the original sound source,

diffuse field represents all of the echoes.
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.
3
6
10
12
20
12
conditions for the types of interaction a sound wave will have with an object in space: long wave, medium freq, high freq

a. object is "invisible"
b. diffraction around object edges (partial sound shadow)
c. complete sound shadow (i.e., object like a brick wall)
object is "invisible" = long wavelength

diffraction around object edges (partial sound shadow) = medium frequency

complete sound shadow (i.e., object like a brick wall) = high freq
T or F: The Fourier Transform is used to convert from the time to the frequency domain
True
T or 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
Describe how interaural time differences are created, and why they are most prevalent at lower frequencies.
- when one ear receives the sound before the other, both ears will not receive the sound at the same time.
- ITD & lower frequencies: directly relate to the sound shadow and diffraction freq impacts. lfreq are passed easier or less attenuated, so the longer wavelengths can pass through your head or to the other ear.
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 motion, and lever transformer.

Area differential between the TM and the stapes footplate is most important due to the ratio between the two that contribute to increased pressure within the oval window. significant - stiletto heel effect - stapes footplate - all of the pressure on one point intense
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?)
lose area transformer no pressure of TM into stapes footplate & orientation of ossicles (lever action)
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).
1. On ground, outside environment same as middle ear

2. Ascend - pressure change - eustachian tube - build up of pressure not equal in pressure around - more pressure in ear than outside

3. Descend - pressure negative inside ear pop
The oval window is in contact with _____ in the middle ear. This structure is number ____ in the figure below.
stapes, 18
What are the three primary roles of the outer ear?
sound localization
protection from foreign objects middle ear +canal
amplify sound pressure
Which scala is connected to the stapes through the oval window?
Scala media
Scala tympani
Scala vestibuli
Scala vestibuli
Which scala is bordered by Reissner's membrane, the organ of Corti, and the stria vascularis?
Scala media
Scala tympani
Scala vestibuli
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
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?
responding to high frequency at the base of the cochlea and responding to low frequencies at the top or apex.
Since octaves are equally spaced along the basilar membrane, which corresponds to a longer distance on basilar membrane
100 to 200 Hz
1000 to 2000 Hz
500 to 1000 Hz
10000 to 20000 Hz
All are equal distance
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?
Damping
Stiffness
Mass
stiffness
Which hair cell type is closer to the modiolus
Inner hair cells
Outer hair cells
inner
A particular stimulus causes three places of maximal displacement of basilar-membrane motion. What is most likely true about the stimulus?
This can't happen - it's a mistake.
It's aperiodic
It's a complex sound, with three frequency components.
It's a transient
It's pink noise.
It's a complex sound, with three frequency components.
Choose which cochlear structure is primarily responsible for the following inner ear potentials: Stria vascularis, inner hair cells, outer hair cells, auditory nerve fibers

Resting potential
stria vascularis
Choose which cochlear structure is primarily responsible for the following inner ear potentials: Stria vascularis, inner hair cells, outer hair cells, auditory nerve fibers
Summating potential
inner hair cells
Choose which cochlear structure is primarily responsible for the following inner ear potentials: Stria vascularis, inner hair cells, outer hair cells, auditory nerve fibers
Cochlear microphonic
outer hair cells
Choose which cochlear structure is primarily responsible for the following inner ear potentials: Stria vascularis, inner hair cells, outer hair cells, auditory nerve fibers
Action Potential
AN fibers
Which hair cells display motile responses? What protein facilitates that fast motile response?
Outer hair cells display a motile response or an active response due to the protein prestin.
Which hair cells release neurotransmitters to send the majority of afferent information to the auditory nerve?
Inner hair cells release neurotransmitters that send majority of afferent information to the AN
Describe two important differences between afferent and efferent auditory nerve fibers.
signal direction; the afferent signals relate to the axonal projections and going to the brain stem, whereas the efferent projections are downward traveling to the cochlea.
What is the main hypothesized function of efferent auditory nerve fibers?
The main hypothesized function of efferent auditory nerve fibers are to be biologically transducers for sound and for cochlear gain control.
Which is not an example of an acoustically driven otoacoustic emission:
Distortion product otoacoustic emissions
Stimulus frequency otoacoustic emissions
Transient evoked otoacoustic emissions
Spontaneous otoacoustic emissions
Spontaneous otoacoustic emissions
Which is not a significant step in the transduction from stapes motion to action-potential generation in auditory-nerve fibers?
a. Stapes motion creates fluid oscillations within the cochlea
b. Traveling wave created and travels down basilar membrane
c. Differential motion between the basilar membrane and tectorial membrane shears the hair-cell stereocilia back and forth
d. Ion channels open as stereocilia move in excitatory direction, allowing potassium to flow into the hair cell
e. Hair cell is hyperpolarized when potassium ions (K+) flow in
f. Neurotransmitter released from the inner hair cell base excites auditory-nerve fiber synapse, creating an action potential
e. Hair cell is hyperpolarized when potassium ions (K+) flow in
Define neural saturation.
Neural saturation is when a nerve fiber cannot increase its firing rate in response to a stimulus
Discuss two issues (one rate-based and one temporal-based) that limit the encoding of sound frequency.
neural saturation and phase locking; within the issues of

rate based
encoding of sound, the saturation limits place coding because once higher sound levels do not impact neurons due to saturation rates, it makes it difficult to determine the actual frequency of the sound.

issue is phase locking within temporal coding; since there is diminishing sound at 4-5kHz, the higher frequencies are limited so the code cannot be compiled as strongly.
Define "phase locking".
Phase locking is the ability of a neuron to synchronize firing to a particular phase of a stimulus. In other words, auditory nerve fibers fire in sync or in phase along the period (cycle) of a sound wave at a given frequency.
sequence the events

action potential, relative refractory period, absolute refractory period
1. action pot
2. absolute refractory period
3. relative refractory
Match the AN-fiber threshold range and spontaneous-rate (SR) group. high medium low threshold
Low-SR
Medium-SR
High-SR
low: high threshold
medium: medium
high: low threshold
Is sound intensity likely to be encoded by a single auditory-nerve fiber?
YES
NO
no
For which neural code is tonotopicity most important?
Rate code
Temporal code
Place code
Volley theory
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
500 Hz
1000 Hz
2000 Hz
8000 Hz
10000 Hz
2000 Hz
Which landmark along the auditory pathway is the first point where binaural processing occurs?
Superior olivary complex
Describe the landmarks that are represented by each wave of the auditory brainstem response (ABR).
auditory nerve (wave I), cochlear nucleus (wave II), superior olivary complex (wave III), lateral lemniscus (wave IV), then finally the inferior colliculus (wave V).

The auditory nerve enters the skull then brainstem at pons and medulla.

CN: encodes different aspects of sound; its outputs go to the SOC, LL, and IC.

SOC: biaural processing occurs and is important for sound localization;

LL receives inputs from the CN and SOC and outputs to the SOC, CN, and IC.

IC core and belt and refines sound localization. input from all caudal structures and is contralateral
Considering the way sound frequency is coded in auditory nerve fibers, why might perceptual frequency discrimination get so much worse above 2 kHz?
Perceptual frequency discrimination is worse above 2kHz due to neural phase locking diminishes above ~2-3 kHz, so temporal coding for frequency gets worse at higher frequencies and this may limit how well we can discriminate sounds.
Which part of the auditory system primarily limits the frequency range of hearing?
Outer ear
Middle ear
Inner ear
Central nervous system
Auditory cortex
middle ear
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