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31 Cards in this Set
- Front
- Back
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Sound travels through air at what speed? |
340 m/s |
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What is the upper limit of audible frequencies? |
20k Hz |
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Loudness, Pitch, and Timbre are the perceptual dimensions of sound. What are the corresponding physical dimensions? |
Amplitude=Loudness Frequency(Hz)=Pitch Complexity=Timbre (combo of diff frequencies) |
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Sound is funneled via the ______ to the ear canal to the ______ membrane which vibrates the middle ear bones. What is the anatomy of the middle ear going from the membrane? |
Pinna to the tympanic membrane. The middle ear consists of maleus (hammer) --> incus --> stapes --> oval window of the cochlea This is in order going from tympanic membrane in to the oval window |
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What is the organization of the inner ear. Describe the longitudinal division, where the structures sit, where the hair cells are, and any pertinent membrane |
The cochlea which is longitudinally divided into the scala vestibuli, scala media, and scala tympani. It contains the organ of corti which sits at the base of the scala media right atop of the basilar membrane. The hair cells of the organ or corti are anchored to the basilar membrane, and some cells connect the basilar membrane to the tectorial membrane which sits like a shelf overhead the organ of corti in the scala media |
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What are the components of the organ or corti? |
1) Basilar membrane 2) Auditory receptor cells aka hair cells (inner and outer hair cells) 3) Tectorial membrane |
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Sound waves cause the ____ membrane to move relative to the ______ membrane which bends cilia of the hair cells causing receptor potential |
basilar membrane moves relative to the tectorial membrane |
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What is the function of the round window and oval window of the cochlea? |
Round window: membrane covered opening that allows the fluid inside the cochlea to move back and forth. Oval window: membrane covered opening that has force exerted on it by the stapes |
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How is the scala vestibuli and scala media separated? How is the scala media and scala tympani separated? |
Scala vestibuli is separated from scala media by reissners membrane Scala tympani and scala media are separated by the basilar membrane |
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Hair cells are anchored to the ______ membrane via rodlike ______ cells. |
basilar membrane via rodlike dieter's cells |
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What are the 3 major differences between inner and outer hair cells? |
1) The inner hair cells are the actual sensory receptors, whereas the outer hair cells are almost all from efferent axons that arise from cells in the brain 2) Destruction of inner cells eliminate hearing, but destruction of outer cells does not 3) The inner hair cells do not touch the tectorial membrane unlike the outer hair cells |
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What is the function of the outer hair cells? |
The outer hair cells sharpen the frequency-resolving power of the cochlea by actively contracting and relaxing, thus changing the stiffness of the tectorial membrane at particular locations. These changes amplify the vibrations of the basilar membrane increasing the sensitivity of the inner ear to sound waves |
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If the inner hair cells do not directly contact the tectorial membrane, how do they bend? What structure in the organ of corti ensures that this can occur? There are diseases in which bone calcifies on top of an organ or corti structure. What is this structure and how do we fix it? |
The relative movement of the two membranes causes the perilymph fluid within the cochlea to flow past them, making them bend back and forth too. This is facilitated by the round window which can be calcified over in certain diseases and can be rectified by fenestration. |
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Cilia are attached to one another via _____ links and these links' point of attachment on the cilia is the ______ plaques. Each _____ plaque contains an ion channel, and movement of the cilia towards the tallest cilia causes _______ via ___ and ____ ions |
Tip links, insertional, insertional, depolarization via calcium and potassium ion flow into the cilia |
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What is the primary afferent auditory pathway starting with the auditory nerve? |
Auditory nerve aka 8th cranial nerve --> Cochlear nuclei of the medulla --> Superior olivary nuclei of the medulla ---> Inferior colliculi of the tectum via the lateral lamniscus --> medial geniculate of the thalamus--> Auditory cortex |
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The basal end of the basilar membrane (the end toward the oval window, which responds to the highest frequencies) is represented most ________ in the auditory cortex, and the apical end is represented most _______ there. This is an example of ______ representation. |
medially, laterally, tonotopic |
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What nerve bundle allows for sharpening of acuity by actively contracting and relaxing outer hair cells, thus changing the stiffness of the tectorial membrane at particular locations? Where does this bundle project from? |
The olivocochlear bundle (OCB) is the nerve bundle that originates in the superior olivary complex of the brainstem which acts efferently upon the outer hair cells |
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How can we locate the primary auditory cortex? What is the first stop in the primary auditory cortex, and then where does that processed info go. |
The primary auditory cortex is hidden in the lateral fissure. Core region --> Belt region (first level of the auditory association cortex) --> parabelt region |
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Where are high and frequency noises place coded in the basilar membrane? What feature of the basilar membrane allows this? |
Higher frequencies produce more displacement at the basal end of the membrane (the end closest to the stapes), lower frequencies are subsequently more apically represented. The basilar membrane is narrower at the base than at the apex. |
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What are the 2 streams of auditory analysis? Where are they located, and what are their functions? |
Anterior stream begins in the anterior parabelt region and is involved with the analysis of complex sounds The posterior stream begins in the posterior parabelt region and is involved with sound localization |
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What is the kinocilium? What are the rest of the cilium called? |
The tallest cilium in a group that are all attached via tip links. The shorter ones are called the stereocilia |
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The frequency of a sound can be detected by place coding. However, the lowest frequencies do not appear to be accounted for in this manner. So how are the lowest frequencies accounted for? |
They are accounted for by rate aka timing code |
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What structure contains all the cell bodies of the auditory nerve? |
The spiral ganglion follows the spiral of the cochlea and gathers all the dendrites of all the hair cells that it innervates |
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The perceived pitch of the note is the waveform shape that repeats itself regularly. We call this the ______ frequency. The actual waveform actually consists of a series of sine waves that includes the ________ frequency and many _______ , multiples of the _______ frequency |
Fundamental, fundamental, overtones, fundamental |
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How do we perceive loudness? |
more intense vibrations of eardrums and ossicles, more intense shearing force on the cilia of the hair cells. Hair cells release more neurotransmitter —> higher rate of cochlear nerve axons firing |
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What three physiological mechanisms detect the location of sound sources? When are each of these used respectively? |
1) Binaural phase differences is used for low frequency sounds 2) Intensity differences for high frequency sounds 3) Analysis of timbre to determine the height of the source of a sound and recognize whether it is in front of us or behind us |
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What brain structure processes phase and intensity difference information? |
Neurons in the superior olivary complex |
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What structure allows us to collect timbre information to determine source sounds? How? |
The Pinna. Depending on the angle at which the sound waves strike these folds and ridges, different frequencies will be enhanced or attenuated, thus the pattern of reflections will change with the location of the source of the sound, which will alter the timbre of the sound that is perceived. |
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Lesions of the bilateral auditory cortex, inferior colliculus, and lateral lemniscus all result in different hearing problems. What are they? |
Bilateral auditory cortex: animal can detect frequency and intensity difference, but not tunes Inferior colliculus: animal cannot detect frequency or intensity differences Lateral lemniscus: animal is deaf |
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What are the 3 general catagories of auditory impairments? How do these arise? |
1) Conduction deafness: Outer or middle ear disorders, vibrations don't reach the cochlea 2) Sensorineural deafness: Cochlear or 8th nerve disorders, auditory stimuli don't reach the brain 3) Central deafness: Disorders/damage of brain auditory regions |
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How is the primary auditory cortex organized? What are the structural analogs of this organization in the visual cortex? |
Vertically oriented columns There are frequency columns which are analogous to the orientation columns of the visual cortex and there are binaural columns which are analogous to the ocular dominance columns of the visual cortex |
