Chapter 13: The Auditory System
20. Refer to the figure. Damage to which region would affect perception of sound the most? a. A b. B c. C d. D e. E
Answer: c
8. Compare the strategies for sound localization via by neurons in the medial superior olive (MSO) versus the lateral superior olive (LSO)/medial nucleus of the trapezoid body (MNTB).
Answer: Sound localization in the MSO relies on interaural time differences for frequencies below 3 kHz. In the case of frequencies above 3 kHz, interaural intensities are responsible for sound localization via the LSO and MNTB.
4. List the steps in stimulus transduction, from the physical sound stimulus to the electrical signals of inner hair cells. Indicate which steps take place in the external, middle, and inner ear.
Answer: Sound waves are gathered in the external ear, and cause the tympanic membrane to vibrate. This vibration is transferred to the oval window of the cochlea via the ossicles of the middle ear. The vibration is transferred to the endolymph in the scala media to move the stereocilia of the hair cells against the tectorial membrane. This creates a shearing force that induces tip links on the stereocilia to modulate the opening of mechanoelectrical transduction channels. An influx of cations then depolarizes the cell, increasing internal Ca2+, and releasing transmitter onto the auditory nerve.
2. What is the audible frequency range in humans (in Hz)? What is the approximate range of human speech sounds?
Answer: The audible range in humans is 20 Hz-20 kHz. The approximate range for human speech is 2-5 kHz.
9. Compare the functions of the inferior colliculus, medial geniculate complex (MGC), and primary auditory cortex.
Answer: The inferior colliculus is important in integrative functions, such as the processing of sound frequencies and integration of localization cues. The MGC is the relay station to the auditory cortex and it is selective for specific frequency combinations and time intervals of sounds. The auditory cortex maps sound tonotopically, and is influenced by other nonauditory information, such speech production.
1. A human's perception of pitch corresponds to the _______ of a sound wave; perception of loudness corresponds to the _______ of a sound wave. a. frequency; amplitude b. amplitude; frequency c. waveform; amplitude d. amplitude; phase e. phase; waveform
Answer: a
10. Which ion and direction of flow is responsible for depolarization of inner hair cells? a. Potassium into the cell b. Potassium out of the cell c. Sodium into the cell d. Sodium out of the cell e. Calcium out of the cell
Answer: a
12. Which structure(s) connect(s) adjacent stereocilia? a. Tip links b. Kinocilium c. Inner hair cells d. Outer hair cells e. Microtubules
Answer: a
14. If efferent axons that travel between the brainstem and cochlea are damaged, leaving the afferent axons intact, which structures would not function properly? a. Outer hair cells b. Inner hair cells c. Kinocilium d. Hair cells in ampullae e. Tectorial membrane
Answer: a
18. Which statement about lemniscal and collicular sound processing is false? a. The different acoustical cell types seen in the inferior colliculus are also present in the cochlear nuclei, but they are not formed into a topographic map at the cochlear level of the pathway. b. Unlike the physical mapping of the visual world onto the retina, the auditory space map in the inferior colliculus is purely a construct of the brainstem's processing of auditory information. c. Certain collicular neurons respond preferentially to frequency-modulated sounds. d. Certain collicular neurons respond preferentially to sounds of a fixed duration. e. The monaural pathway connects the cochlear nucleus to the midbrain via the nuclei of the lateral lemniscus.
Answer: a
19. Which of the following could a human ear transduce most optimally? a. A conversation b. A thunderstorm c. A dog barking d. A plane taking off e. A computerized tone
Answer: a
21. A 500-Hz signal from a speaker located to the left of a study participant will reach its target neuron in the ______ superior olive from the left ear _______ compared to the same neuron from the right ear. a. medial; sooner b. medial; later c. medial; at the same time d. lateral; sooner e. lateral; later
Answer: a
23. Which statement about the nuclei of the lateral lemniscus is false? a. Their output converges at the pons. b. They receive input from the cochlear nucleus. c. They respond to monaural sound. d. They process duration of sound. e. They process onset of sound.
Answer: a
28. If a subject undergoes an MRI scan while listens to their favorite song, which area of the brain would you expect to show the greatest activity? a. Right belt b. Right core c. Left belt d. Left core e. All brain areas would show similar activity
Answer: a
4. Which statement about the functioning of cochlear implants (CIs) is false? a. They are designed to induce electromechanical pressure waves within the cochlear fluid. b. They require an electrical connection from an implanted stimulator to a cochlear electrode array. c. They provide tonotopic delivery of electrical signals along the length of the cochlea. d. They require an auditory signal processing device that decomposes sounds into component frequencies. e. They electrically stimulate residual hair cells and/or primary auditory afferents.
Answer: a
11. Why is the flexibility of the round window vital for proper functioning of the cochlea? a. It is responsible for the differing flexibility of the basilar membrane. b. There must be a space for liquid to move after displacement from the oval window because liquid does not compress. c. It gives rise to the topographical mapping of frequency in the cochlea, which allows for the decomposition of sound. d. The traveling wave in the fluid produces a shearing motion of the hair cells, which causes a voltage change in the round window. e. It allows for a traveling wave to reach a point of maximum displacement based on its frequency.
Answer: b
14. Which of the following is responsible for the biphasic receptor potential of hair cells? a. Differing ionic properties between the surrounding perilymph and endolymph b. Transduction channels that are open at rest c. Increases in intracellular calcium causing transmitter release d. Ion-pumping cells in the stria vascularis increasing intracellular potassium stores e. Gap junctions along the apical and basal surfaces
Answer: b
16. Which auditory property most depends upon the utilization of bilateral auditory information? a. Frequency discrimination b. Sound localization c. Distinguishing pitch from timbre d. Encoding of speech sounds e. Detection of very faint sounds
Answer: b
17. Spontaneous otoacoustic emissions can cause which of the following auditory problems? a. Deafness b. Tinnitus c. Presbyacusis d. Ossification of the ossicles e. Auditory nerve damage
Answer: b
25. The auditory cortex is located on the _______ gyri within the _______ sulcus. a. fusiform; lateral b. superior temporal; lateral c. inferior temporal; lateral d. transverse temporal; central e. fusiform; central
Answer: b
6. Where does central processing first occur along the auditory pathway? a. Tympanic Membrane b. Cochlear nucleus c. Concha d. Superior olivary complex e. Inferior colliculus
Answer: b
8. Which statement about sensory transduction by hair cells is false? a. Bending of the cilia toward the longest cilium produces depolarization. b. The electrical activity initiated by the tip links is transmitted to the vesicular release sites along microtubules that undergo voltage-dependent rearrangements. c. The hair cell body (basal end) is bathed in perilymph, while the hair cell cilia are bathed in endolymph. d. Hair cells are presynaptic to second-order sensory neurons. e. The firing of action potentials in second-order sensory neurons can be either up- or down-regulated, depending on the direction in which the bundle of cilia (of the afferent hair cell) is bent.
Answer: b
9. What quality gives rise to tonotopy along the cochlea? a. The changing width and stiffness of the tectorial membrane b. The changing width and stiffness of the basilar membrane c. The speed at which sound waves propagate along the length of the cochlea d. The changing mechanical properties of the cochlear wall along the length of the cochlea e. The increasing density of the cochlear fluid along the length of the cochlea
Answer: b
1. In order to increase the decibel measurement of a sound, one would have to alter its wave a. form. b. phase. c. amplitude. d. frequency. e. length.
Answer: c
15. Which of the following correctly pairs an auditory pathway location with its input? a. Superior olive—ipsilateral auditory nerve b. Inferior colliculus—axons from both cochlear nuclei and contralateral superior olive c. Nucleus of lateral lemniscus—axons from contralateral cochlear nucleus d. Medial geniculate complex—axons from ipsilateral superior colliculus e. Cochlear nuclei—contralateral auditory nerve
Answer: c
16. In the inner ear, evidence suggests that the _______ is(are) an essential component of the cochlear amplifier. a. tectorial membrane b. stria vascularis c. outer hair cells d. endolymph e. scala media
Answer: c
20. The auditory nerve connects the _______ of the cochlea to the _______ in the medulla. a. spiral ganglion processes; inferior colliculus b. cochlear nucleus; inferior colliculus c. spiral ganglion processes; cochlear nucleus d. cochlear nucleus; spiral ganglion processes e. inferior colliculus; cochlear nucleus
Answer: c
26. A woman has a stroke that damages her secondary auditory cortex. Which sounds will she have the most trouble making sense of? a. Sounds of nature b. Computerized tones c. Speech d. Car horns e. White noise
Answer: c
3. Which of the following would cause conductive hearing loss? a. Damage to the auditory nerve b. Genetic predisposition to hair cell damage c. Ossification of the middle ear bones d. Frequent exposure to gunfire sounds e. Attending many loud concerts
Answer: c
5. Which function is not an operation of the outer ear? a. Boosting sound pressure level as it enters the ear b. Filtering sound in an adaptive manner based on source elevation c. Directing different frequencies of sound to specific cochlear locations d. Optimally transmitting sounds in our range of vocalizations e. Boosting frequencies by means of passive resonances
Answer: c
6. Which action is the primary function of the three bones in the middle ear? a. Selective transmission of high-frequency sounds b. Selective transmission of low-frequency sounds c. Amplification of sound pressure waves to increase auditory sensitivity d. Dampening sound pressure waves to prevent damage to the ear e. Facilitation of fluid drainage from the Eustachian tube
Answer: c
9. What is the main function of the ossicles? a. Reduce energy transfer to the cochlea from loud noises b. Reduce pressure in the middle ear c. Transfer vibrations from the tympanic membrane to the oval window d. Convert sound vibrations into neural impulses e. Provide cues for elevation of high frequency sound sources
Answer: c
12. What is the difference between the endolymph and perilymph? a. Perilymph is high in potassium and low in sodium; endolymph is high in sodium and low in potassium. b. Endolymph is high in potassium; perilymph is high in both potassium and calcium. c. Perilymph is located in the semicircular canals; endolymph is located in the cochlea. d. Endolymph is high in potassium and low in sodium; perilymph is high in sodium and low in potassium. e. The composition of perilymph is important for proper hair cell functioning; the composition of endolymph does not have effect hair cell functioning.
Answer: d
13. A student who is working on a cure hearing loss develops a hair cell MET channel agonist. Would you expect this drug to be effective? Why? a. Yes; it would increase the flow of cations into the hair cell. b. Yes; it would open the MET channel without sound stimuli. c. Yes; it would induce a second messenger cascade that will hold MET channels open longer. d. No; the MET channel can only be altered by mechanical means. e. No; it would decrease the flow of cations into the hair cell.
Answer: d
18. A scientist studying auditory transmission of low frequencies would take a recording from nerves at the _______ of the cochlea and look for _______ firing in response to a stimulus. a. base; constant b. base; phase locked c. apex; constant d. apex; phase locked e. apex; out of phase
Answer: d
19. Cells with pronounced selectivity for specific combinations of sound frequencies are found in the a. ventral cochlear nucleus. b. nuclei of the lateral lemniscus. c. inferior colliculus. d. medial geniculate complex. e. lateral and medial superior olives.
Answer: d
24. Which part of the brain precisely maps sound tonotopically? a. Belt region b. Parabelt region c. Medial geniculate complex d. Core region e. Inferior colliculus
Answer: d
27. Which of the following best supports the notion that the auditory cortex is influenced by nonauditory information? a. Electrophysiological recordings reveal that primary auditory neurons have decreased response to sounds played in reverse. b. Neural responses to speech spread from posterior to anterior regions of the superior temporal gyrus. c. Alternating patches of EE and EI neurons are found near the tonotopic map. d. Auditory cortex activity decreases during speech production. e. Damage to the auditory cortex reveals an inability to discriminate temporal differences in speech.
Answer: d
4. A father notices that his daughter does not respond to him when she isn't facing him, nor does she turn her head toward loud noises. After several appointments with doctors, the family is informed that the girl has malformed hair cells, but has fully functioning auditory nerves. What type of hearing loss does this girl have, and what would be the best treatment option? a. Conductive hearing loss; traditional hearing aid b. Conductive hearing loss; cochlear implant c. Sensorineural hearing loss; traditional hearing aid d. Sensorineural hearing loss; cochlear implant e. Sensorineural hearing loss; brainstem implant
Answer: d
5. Which frequency would be detected by a 23-year-old female with normal hearing, but not be heard by a 72-year-old man with normal hearing? a. 10 Hz b. 300 Hz c. 5 kHz d. 20 kHz e. 40 kHz
Answer: d
8. Hearing loss in the range of _______ is most detrimental to speech recognition. a. 20-50 Hz b. 100-400 Hz c. 700-900 Hz d. 2-5 kHz e. 15-20 kHz
Answer: d
10. The _______ allows _______ to flow between the chambers on either side of the _______ membrane. a. round window; helicotrema; basilar b. perilymph; helicotrema; basilar c. round window; perilymph; tectorial d. oval window; helicotrema; tectorial e. helicotrema; perilymph; basilar
Answer: e
11. In which way is the mechanism of hair-cell transduction distinct from sensory transduction mechanisms that occur outside the ear? a. Potassium influx from the endolymph depolarizes the hair cell. b. Potassium efflux into the perilymph repolarizes the hair cell. c. Calcium and calcium-activated potassium channels contribute to electromechanical resonance. d. The two domains of the hair cell operate, in effect, as two distinct compartments, each with its own ionic equilibrium potentials. e. All of the above
Answer: e
13. Which statement about auditory nerve fibers is false? a. Afferent fibers receive input from inner hair cells. b. Efferent fibers innervate the three rows of outer hair cells. c. The characteristic frequency of the hair cells varies systematically along the cochlear axis. d. The higher frequency fibers can respond well to stimuli at frequencies in the 10 to 20 kHz range. e. The lower frequency fibers have a sharp tuning peak plus a separate extended hump.
Answer: e
15. How does ionic composition of endolymph differ from most extracellular fluids? a. It is K+-poor and Na+-rich. b. It is Ca2+-poor and Na+-rich. c. It is K+-rich and Na+-rich. d. It is Ca2+-poor and Na+-poor. e. It is K+-rich and Na+-poor.
Answer: e
17. In which brain region are the intensities (not the phases) of impinging sound waves compared in order to determine the location of sound sources? a. Cochlear nucleus b. Inferior colliculus c. Medial geniculate complex d. Medial superior olive e. Lateral superior olive
Answer: e
2. For which sound energy would a Fourier transform be most useful in breaking down the frequency spectrum into its component waves? a. Wind b. White noise c. Running water d. Rain e. A duet
Answer: e
2. Which statement about the audible spectrum is false? a. Children can often hear frequencies that adults cannot. b. Small animals are often more sensitive to higher frequencies than larger animals. c. Animals that echolocate often rely on very high-frequency sounds. d. Large predators often make low-frequency sounds as they approach their prey. e. Collectively, mammals can only hear tones at frequencies ranging from 20 Hz to 20 kHz.
Answer: e
22. The lateral superior olive uses which of the following properties of interaural sound for localization? a. Time b. Frequency c. Waveform d. Period e. Intensity
Answer: e
3. Which of the following is not a cause of hearing loss? a. Acoustic trauma b. Ototoxic drugs c. Aging d. All of the above are causes of hearing loss. e. None of the above are causes of hearing loss.
Answer: e
7. Which structure is not part of the external ear? a. Tympanic membrane b. Concha c. Pinna d. Auditory meatus e. Cochlea
Answer: e
9. Research into the biology of those stem cells that generate cochlear hair cells during development could be valuable because a. hair cells are quite sensitive to damage. b. humans begin life with a relatively small number (~15,000 per cochlea) of hair cells. c. mammalian hair cells do not regenerate themselves. d. understanding the basic mechanisms of hair-cell development may suggest therapeutic approaches. e. All of the above
Answer: e