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32 Cards in this Set
- Front
- Back
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5 basics of sound |
- hertz: pitch; cycles of sound per second - amplitude/intensity: loudness - pure tone: tone of a single frequency - musical tone: modualted pure tones with rhythm - noise: random sounds - auditory brain's first task is to discern what is noise and what is not |
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fourier analysis |
- "cat" is 4 different soundwaves blended together |
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sound frequencies in elephants vs humans vs cats |
- elephants can hear lower frequencies than humans - cats can hear higher frequencies than humans |
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what does the ear do with sound, a mechanical force? external ear three ossicles |
- ear tranduces sound into neural activity - external ear and ear canal collects low frequencies - three ossicles: malleus, incus, stapes connect tympanic membrane (eardrum) to oval window |
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oval window is what? two muscles in middle ear links ossicles and oval window? |
- oval window is window to cochlea - two muscles: tensor tympani; stapedius - when activated too much, muscles stiffen and pull from oval window to dampen loudness |
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what fluid is in cochlea? what does vasilar membrane allow? |
- endolymph fluid - vasilar membrane allows hearing by transferring vibration energy to neural |
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where is the tectorial membrane in relation to the ear hairs? what if it wasn't in that exact location? |
- stuck into ear hairs - if not stuck in hairs: vertigo or hearing loss |
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what are tip links? what are stereocilia? how do ear hairs connect with gated ion channels? |
- stereocilia are in various sizes: short medium long - stereocilia are in each hair cell; tip links are thin fibers than run across each stereocilia, linking them together like a bridge - if hairs move by vibrations from basal membrane fluid vibration, mechanical gated ions open and calcium comes into vesicles of the hair cell |
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explain process of sound affecting stereocilia on hair cells |
1. vibrations make stereocilia bend, opening gated ion channels 2. hair cell polarizes and base of hair cell gets a calcium influx, causing glutamate release
- hair cells don't have axons, so they don't have axon potentials |
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outer hair cells act as what? inner hair cells act as what? |
- outer hair cells: amplifiers - inner hair cells: transducers - they connect to spiral ganglion cells and auditory nerve and to brain |
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describe auditory pathway to brain what is superior olivary nuclei? why are there cross overs in the pathway? |
- cochlea passes sound to cochlear nucleus and pons; to superior olivary nuclei; to inferior colliculus; to medial geniculate nucelus; to auditory cortex in brain - superior olivary nuclei: first place with bilateral input - cross overs: each ear sens info to each cortex b/c losing hearing in one ear is very plausible |
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what is tonotopic organization? |
- how auditory neurons are organized - high in the back; high inside - high frequencies are heard inside the ear while lower frequencies are heard toward the outer ear |
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how specialized are auditory cells? |
some auditory cortex cells specialize specifically in what frequency they fire to, but there are other auditory cells that are less picky |
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explain frequency coding, an idea of how we hear sound volley principle? |
- frequency coding: firing rate of auditory neurons encodes pitch: 50 Hz sound causes an auditory cell to fire 50 times/second - low frequencies are frequency coded: up to 50 Hz - volley principle: frequency of the sound wave is too high for any single fiber to fire every cycle - so each fiber only fires at a certain point in the cycle though it does not respond to each cycle |
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explain place coding, an idea of how we hear sound |
- each place on basilar membrane has a resonant frequency, like tuning a guitar - high frequencies are place coded: over 5000 Hz |
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how are intermediate frequencies coded? |
50 to 5000 Hz pitch is coded by a combo of volley and place coding |
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what do binaural cues signal? intensity differences? latency differences? where is localization processed? what does it require? |
- binaural cues signal sound location - intensity differences: different loudness at two ears - latency differences: different arrival times for sound at the ears (more subtly) - accurate localization requires both intensity and latency differences - superior olive is main sound localization nucleus |
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for high frequency sounds, location is coded by what in where? |
- coded by intensity differences in superior olive - intensity differences - lateral SO (superior olive) - compares loudness |
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for low frequency sounds, location is coded by what in where? |
- coded by latency differences in superior olive - time difference - medial SO (superior olive) compares meeting times - coincidence detector |
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auditory cortex analyzes complex sounds in two streams: dorsal stream ventral stream explain |
dorsal: frontoparietal lobe; involved in sound location, where
ventral: temporal lobe; analyzes components of sound; what |
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auditory cortex responds to three different sounds |
random sounds speech environmental sounds: inferior frontal cortex and posterior middle temporal gyrus |
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trained shift in tuning an auditory cell's receptive field: 3 examples of certain learned sounds |
learning a new language learning to listen to music learning your baby's voice
conditioned-stimulus frequency |
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3 categories of deafness |
- conduction deafness: disorders of outer or middle ear that prevent sounds from reaching the cochlea; hole in heardrum - sensorineural deafness: from cochlea or auditory lesions; damage to ear hair - central deafness: caused by brain lesions with complex results; brain stem; hallucinations; rarest |
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central hearing loss: affected areas associated neurological disorders 2 types |
- areas: cortex, brainstem, ascending auditory pathways - disorders: multiple sclerosis, tumors - types: -cortical deafness: pure word deafness and auditory agnosia - auditory hallucinations |
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auditory agnosia pure word deafness |
- auditory agnosia: relatively normal pure tone hearing but inability to recognize verbal or nonverbal sounds, such as ringing telephone vs barking dog - pure word deafness: a type of auditory agnosia, fluent verbal output, severely disturbed spoken language comprehension; nonverbal sounds are correctly indentified; hears every word, but can't hear speech |
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auditory hallucinations what where |
- illusion of complex sound such as music or speech - especially in schizophrenia; injury to secondary auditory cortex; or during a temporal lobe seizure - occasionally auditory hallucinations happen when brainstem damage in superior olive |
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3 causes of conductive hearing loss: middle ear
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otitis media (infection in middle ear) TM perforation (hole in ear drum) ossicular arthritis (abstruction of ear bone joints) |
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sensorineural hearing loss SNHL characteristics causes |
dysfunction of hair cells or auditory nerve inappropriately loud voice high frequency loss is common speech sounds are distorted background noise makes it difficult to hear
viral infections can cause SNHL (measles and CMV) b/c kills developing hair cells ear hair cannot reproduce |
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noise induced hearing loss NIHL |
loss can be sudden, as from an explosion more often unnoticed gradual onset majority of musicians have this #1 preventable cause of deafness |
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presbycusis |
age related hearing loss cannot hear high frequencies as you get older |
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tinnitus what? 2 examples? |
15% of population damage to cochlea initiates tinnitus CNS maintains chronic tinnitus - outer hair cells turn up the volume via efferent connections in response to hearing loss b/c death of inner hair cells - auditory cortex, inferior colliculus, cochlear nucleus all contribute |
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what does anterior cortex process? |
low frequency sounds |
