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230 Cards in this Set
- Front
- Back
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Physical definition sound
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pressure changes in air or other medium
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Perceptual definition sound
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the experience we have when we hear
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Objects make sound by…
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moving back and forth rapidly (20 to 20,000 times per second) through air
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Speaker makes sound by…
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push air molecules together, pull air molecules apart, cycle! --> wave
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sound waves are (lin/long)
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longitudinal - particle's motion is parallel to wave's direction of travel
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Pure tones
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simplest sound wave - sinusoidal pressure variation
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Amplitude
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difference in pressure between high, low peak
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Objective measure of sound
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uPa (micropascals)
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Measure of loudness (subjective)
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dB (decibels)
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Logarithms
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log_10 (10^5) = 5 … each unit increase represents 10 fold increase in raw value
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number of dB
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dB = 20 log 10(p/p0) where p0 is usually 20 uPa
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Response compression
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compensated for by logarithmic scale - each increase by 1 dB is same increase in loudness
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relative amplitude --> dB
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x10 increase in amplitude = +20 decibels
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Frequency
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number of cycles/time (Hz) -- related to pitch!
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Tone height
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increase in pitch when frequency changes
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Periodic tones
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repeating struture! (pure or complex); repetition rate = fundamental f
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Complex tone
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many pure tones (harmonics)
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First harmonic
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pure tone with frequency equal to fundamental f; multiples = higher harmonics
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Frequency spectrum
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represents strength of different components of complex tone
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Natural sounds
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combination of MANY pure tones, relative energy at different f determines pitch; good musical instruments are mostly harmonics
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Musical scales and frequency
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same letter = tone chroma (frequencies are multiples of each other)
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Human hearing range
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20-20,000 Hz; greatest sensitivity 2,000 to 4,000
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Audibility curve
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shows threshold for hearing (most sensitive to speech range)
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Auditory response area
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falls between audibility curve and threshold for feeling
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Threshold of feeling
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pain threshold! Sounds above this amplitude HURT
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Equal loudness curve
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show amplitude necessary to produce same perception at different f
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sound quality
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All other properties EXCEPT loudness and pitch = timbre
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Timbre
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multiple frequencies; attack of tones & decay of tones (curved peak)
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Outer ear
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Pinna, auditory canal, tympanic membrane
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Pinna
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sound location
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Auditory canal
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3 cm long tube like structure, protects tympanic membrane (end of canal)
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Resonant frequency of canal
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amplifies 2,000 to 5,000 (max sensitivity to human speech)
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Middle ear
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2 cm3 cavity separating inner from outer ear
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3 ossicles
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malleus (moves due to vibration), incus (transmits vibration of malleus), stapes (transmits incus to inner ear via cochlea)
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ossicles purpose
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focus and amplify vibrations; transfer from air to fluid
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Inner ear
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COCHLEA
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Cochlea
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fluid filled, stapes vibrates, divided into scala vestibuli and scala tympani
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Cochlear partition
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extends from stapes (base) to apex (far end), contains organ of corti
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Organ of Corti
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Basilar membrane vibrates in response to sound; inner/outer hair cells are receptors; tectorial membrane covers hair cells
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Transduction
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interaction of these 3 structures (vibration of hair cells); stretching of tip links opens K+ channels, hair cells release neurotransmitters --> firing nerve fibers
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Neural signals for frequency
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1) which fibers respond (specific hair cells activate specific nerves); 2) how fibers fire (rate or pattern of firing --> nerve impulses)
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Bekesy's place theory of hearing
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frequency of sound indicated by PLACE on organ of Corti with highest firing; direct observation of basilar membrane in cadaver + building model of cochlea
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Basilar membrane properties
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base is 3-4x narrower than apex; 100 times stiffer than apex -- vibration = traveling wave
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Shape of traveling wave
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envelope (lines indicatiing max displacement) -- hair cells at PEAK are stimulated most; position of peak is fn(f)
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Tonotopic map
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Cochlea shows orderly map of frequencies along its length(apex = low Hz, base = high Hz)
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Neural frequency tuning curve
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pure tones -- determine threshold for specific frequencies; plot threshold for frequency = tuning curve
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characteristic frequency
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frequency to which neuron is most sensitive
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Fourier analysis
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separate complex waveform into sine waves; cochlea is frequency analyzer (high neuronal response -- characteristic frequencies correspond with sine-wave components)
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Frequency coding
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which fibers fire, how they fire; auditory nerve fibers fire in bursts (at peak of sine-wave stimulus), groups of fibers fire together with silent intervals that create patterns of firing! (different frequency = different pattern) NO GOOD ABOVE 5000 Hz
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Cochlear implant
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bypass damaged portion of ear; directly stimulate auditory nerve, must learn how to use!
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Cochlear implant makeup
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microphone behind ear, sound processor, transmitter, receiver (both on mastoid bone)
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Cochlear implant mechanism
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stimulate cochlea at different places on tonotopic map; receive early in life to learn how to use it!
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infant hearing
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audibility curves higher (min dB higher); 2-day old infants can recognize mothers' voice
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Tonotopic map - cochlear nucleus
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ventral = low, dorsal = high
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Bushy cells
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code for different frequencies, reciprocal inhibition (sharper Hz)
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stellate cells
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fire for duration of stimulus; rate indicates intensity
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octopus cells
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fire at start/stop (timing info)
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Superior olivary nucleus
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tonotopic, binaural activity (1st site), horizontal sound direction
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Inferior colliculus
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input from A1, may be switchboard for auditory attention, integrates multi-modal perceptions (next to superior colliculus)
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Medial Geniculate Nucleus
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nucleus of thalamus (similar to LGN - vision), all aspects of sound, pitch perception (complex!)
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Auditory cortex
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A1 --> core --> belt --> parabelt (core=simple, belt+parabelt=complex)
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Tonotopic map training
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owl monkeys -- tonotopic maps enlarged for 2500 Hz if trained
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Auditory cortex damage
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pitch perception difficulties
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Human brain scans
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core = pitch recognition; parabelt = complex stimuli
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Experience and auditory cortex
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Musicians have enlarged auditory compex; marmosets trained to lick water spout in response to one tone (in a series of music)
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Eye vs ear
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retinotopic is location; tonotopic is pitch… how do we find sounds' location?
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Auditory localization
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auditory space surrounds observer; exists with all sounds; most accurate in front
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Asimuth coordinates
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position left to right
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elevation coordinates
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position up and down
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distance coordinates
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position from observer
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interaural time difference
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binaural cue-- works best for low Hz sounds (difference in time -- difference in distance
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interaural level difference
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binaural cue -- difference in sound pressure level hitting two hears (high Hz sounds have acoustic shadow cast by head)
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cone of confusion
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binaural cues don't resolve ambiguity--especially for elevation1
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monaural cue
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pinna and head affect frequencies -- spectral cue! (Hz spectrum -- location info)
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pinna mold experiment
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fitted with mold, immediately unable to detect elevation; eventually adjusted!
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sound localization in brain
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InterauralTimeDifference neurons… overlap of signals over 10 neurons determines distance
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Interaural time-difference detectors
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found in A1, superior olivary nucleus (first nucleus to receive biaural input)
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topographic map
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neural structure that responds to spatial location
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topographic neurons
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barn owls have them; mammals have maps in subcortical structure (inferior colliculus) with receptive field for location
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birds and mammals
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birds - narrow tuning curves; mammals - wide tuning curves (ratio of responses)
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what stream
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ventral - anterior core, belt --> prefrontal cortex (identify sounds)
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where stream
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dorsal - posterior core, belt --> parietal + prefrontal cortex (locate sound)
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direct sound
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sound that reaches listener's ears directly
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indirect sound
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reflected off environmental surfaces and then to listener
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Litovsky et al
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two speakers - time difference (5-20 msec not perceived)
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Reverberation time
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time it takes sound to decrease by 1/1000th of pressure (ideal 2 sec)
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Intimacy time
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time between sound leaving source and first reflection arriving (20ms)
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Bass ratio
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ratio of low to middle frequencies reflected (high bass - best)
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spaciousness factor
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fraction of all sound that is indirect (the more the better!)
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Classrooms
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.4 to .6 s (small), 1-1.5 s (large) - hear voices clearly; +10 or +15 dB signal:noise
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Auditory scene
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array of all sound sources in environment
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auditory scene analysis
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process by which these sounds are separated and perceived -- NOT in the cochlea!
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brain's role in ASA
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segregate sound from different sources; group separate sounds from same source -- ill posed problem!
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Auditory grouping principles
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location, smooth motion, onset times, similarity, auditory continuity
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Location
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single sound source tends to come from one location
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Smooth motion
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single sound source tends to move continuously
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Onset times
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sounds that start at different times come from different sources
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Similarity
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single sound source tends to produce sounds of similar pitch, timbre
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auditory continuity
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sounds that stay constant OR change smoothly are grouped
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experience
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stuff we're familiar with gets grouped together
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perceiving metric (rhythm)
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physical motion, language experience determine perception of ambiguous rhythm
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Articulation
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vocal cord use, position of tongue/lips/teeth/soft palate! All determine sound
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Spectogram
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X axis - time, Y axis - frequency, darker = greater amplitude
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Vowels
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pressure peaks at different frequencies -- formants (a, e, o, I, u, etc)
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Consonants
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restrict or stop flow of air -- differences in on/offset of formants (formant transitions)
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consonant onset time
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onset time -- time that passes from onset of sound before vocal cords engage (d, t differ by 74 ms)
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Categorical perception
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perceived categorically -- we'd never say a sound is halfway between t and d!
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Phonemes
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smallest unit of speech that changes meaning of word
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minimal pair
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words that differ in one phoneme
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Speech perception
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separate speech from surrounding noise; segment speech into sounds/words (find phonemes and words)
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Identifying phonemes?
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hard because pronunciation changes depending on preceding, succeeding sound, placement (coarticulation)
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Variability of phonemes
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different people produce phonemes differently
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Word superiority effect
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phonemes more easily identified in real words
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Turvey/Van Gelder
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short words, short non-words presented to listeners; asked to find certain phoneme (faster for words than non-words)
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phonemic restoration
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works even in noisy environments; mentally fill in missing sound using context
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identifying words
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hard - pauses rare, some pauses IN WORDS, not always fully articulated (whatchapto?)
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Mondegreen
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misparsing of speech
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Miller, Isard
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grammatical sentences, weird but grammatical sentences, ungrammatical word strings; repeat sentences - high accuracy for sentences, much lower for ungrammatical word sttrings
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Visual cues for identifying
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info from speaker's mouth aids in speech perception
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McGurk effect
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mouth movements don't match? We hear a different sound
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Colvert et al
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same brain areas for lip reading, speech perception
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Statistical learning in identifying words
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knowledge of word structure -- transitional probabilities (chances that one sound will follow another)
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Saffran et al
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infants experience statistical learning -- nonsense words containing transitional probabilities; mixed up --> listen longer!
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speaker characteristics
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age, gender, emotional state, level of seriousness - affect identification
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Palmeri et al
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indicate when word was new in a sequence; MUCH faster if same speaker used repeatedly
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Broca's aphasia
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damage to Broca's area = labored speech, but good understanding
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Wernicke's aphasia
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damage to Wernicke's area (temporal lobe) = "fluent" but meaningless speech, difficulty understanding others
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Voice area
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STS - affected more by voices than other sounds
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Dual stream model
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ventral stream recognize speech, dorsal stream links acoustic signal to movements for producing speech
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Pasley experiment
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how pattern of electrical signals represents sounds; speech decoder!
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Motor theory of speech
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motor mechanisms responsible for producing sounds activate mechanisms for perceiving sound
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D'Ausiliao TMS exp.
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link between production and perception; useful but not required (most likely)
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Babies and speech perception
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1 month old --> categorical perception; aging causes loss of ability to perceive phonemes not in their language
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Cutaneous senses
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perception of touch and pain from stimulation of skin
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proprioception
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ability to sense position of body, limbs
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kinesthesis
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ability to sense movement of body and limbs
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Skin
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heaviest organ in body, protects organism, epidermis (dead skin cells), dermis contains mechanoreceptors that respond to stimuli
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Touch receptors
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grouped by depth in skin, speed of adaptation
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Merkel receptors
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SA1 (shallow, slow adapting, responsible for sensing fine details)
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Meissner corpuscles
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RA1 (shallow, rapid adapting, controls hand grip)
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Ruffini cylinders
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SA2 (deep, slow adapting, perceiving stretching)
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Pacinian corpuscles
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RA2 (deep, rapid adapting, sense rapid vibrations and texture w/ movement)
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Slow adapting receptors
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better for detail (SA1 responds to grooves; RA2 does not!)
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Depth of receptor
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deeper receptors = larger receptive field
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Free nerve endings
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5th mechanoreceptor? Variety of sensations; can be rapid or slow
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Skin to cortex
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peripheral nerves to spinal cords; 2 pathways that cross over, synapse in thalamus to S1, S2 (parietal lobe)
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medial lemniscal pathway
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large fibers, proprioceptive and touch info
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spinothalamic pathway
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smaller fibers that carry temperature, pain
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homunculus
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more cortical space for parts of body responsible for detail
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Experience dependent plasticity
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use one area more -- more area in cortex! (violinists -- left hand fingertips)
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Plasticity
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phantom limb - cortical reorganization after amputation
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Rubber hand illusion
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subject feels that rubber hand is their own
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Tactile acuity
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two methods - two point threshold, grating acuity
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two-point threshold
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participant is touched with one or two probes…measure threshold!
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grating orientation
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determine if grating is horizontal or vertical (measure threshold spatial frequency)
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individual differences in tactile acuity
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decreases with age; females more sensitive, genetic, correlated with hearing
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Receptors for tactile acuity
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high density of Merkel receptors in fingers (like cones in fovea)
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Cortex and tactile acuity
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high acuity? More area of cortical tissue
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Tactile receptive fields
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much smaller in some areas (fingertips, lips) than others (forearm, back)
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Perceiving vibration
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Pacinian corpuscle; nerve fibers respond to vibration (there's a corpuscle in the way!)
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Perceiving texture
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spatial cues, temporal cues (two receptors = duplex theory of texture perception)
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Texture adaptation experiment
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adapt to 10 Hz stimulus for RA1, 250 Hz stimulus for PC; only PC affects fine texture perception
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Haptic exploration
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active exploration of 3D objects with hand - uses lots of brain areas
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Haptic exploratory procedures
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lateral motion, contour following, pressure, enclosure
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Physiology of object perception
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firing pattern of mechanoreceptors signals shape; upstream neurons more specialized, S1 has cells that respond to attention, orientation/direction, specific objects
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Tactile attention
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attend to touch sensations! Endogenous is top-down; exogenous captures attention; attentional cueing speeds response, susceptible to change blindness!
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Haptic search
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nearly preattentive for cube in spheres; ellipse among spheres harder
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Tactile agnosia (astereognosia)
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inability to recognize objects through touch
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asomatognosia
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failure to recognize parts of one's own body!
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thermoreceptors
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dermis and epidermis, signal changes in temperature; cold fibers 30:1, ambient or object temp, extreme temp -- PAIN
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inflammatory pain
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damage to tissues and joints; tumor cells
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neuropathic pain
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damage to CNS (stroke, carpal tunnel)
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nociceptive
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signals impending damage to skin (heat, chemical, pressure, cold)
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Gate control
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SG-, SG+ cells (CNS control goes to -, mechanoreceptors (L) to -, nociceptors (S) to +)
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Pain in brain?
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no pain cortex; spinothalamic pathway --> HT, limbic, thalamus, S1, insula, ACC
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opioids
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endogenous = endorphins (pain, pleasure); exogenous mimics endorphins
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naloxone
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treat heroin, morphine overdoes; blocks receptor site (pain up!), decreases effectiveness of placebos!
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placebo effect
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endorphins; location-specific!
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Cognition and pain
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expectation, attention, distraction, hypnotic suggestion all affect pain perception
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distraction on pain
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use positive stimuli to distract!
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hypnotic suggestion
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fMRI, subjective reports show hypnosis DID produce pain!
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unpleasantness vs pain
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suggestion to change intensity led to change in ratings and S1; change unpleasantness also had desired effect
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Eisenberger - emotional pain
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players "left out" of computer game - activity in ACC
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observing vs. experiencing
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similar brain areas activated whether observe or experiences
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Pain, itch
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itch inhibited by pain receptors, stimulated by pain-blockers
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itch receptors
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C nerve fibers, lateral spinothalamic tract, only close to surface! (no internal itching…thank goodness!)
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itch in the brain
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pattern of activation similar (not identical) to pain sensation
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Chemical senses
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act as gatekeepers, facilitate memory, involved in mate selection (maybe…)
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Taste system
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tongue contains papillae
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filiform
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shaped like cones, over entire tongue
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fungiform
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shaped like mushrooms; found on sides and tip of tongue
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foliate
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folds on back and sides
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circumvallate
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flat mounds in a trench located at back
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Taste buds
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inside papillae EXCEPT filiform; 10,000 taste buds, cells with tips into taste pore (transduction occurs if chemicals contact receptors on tips)
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tongue map?
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NOT TRUE
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supertasters
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may more fungiform papillae, avoid bitter flavors
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taste development
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sweet, bitter developed at birth; salty less developed
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Taste signals
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chorda tympani nerve from front, sides of tongue; glossopharyngeal nervue from back of tongue, vagus nerve from mouth/throat, superficial petronasal nerve from soft palate
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Taste signal pathways
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connect in nucleus of solitary tract; into thalamus, then frontal lobe (insula, OFC, frontal operculu)
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Salty
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receptors respond to NaCl, sodium important; low-sodium diet increases intensity of salt; early experiences modify preferences!
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sour
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H+ ions; combined with sweet = fruit but with bitter = poison!
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sweet
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carbohydrates in solution (pleasant, high calories, glucose, fructose, or sucrose; one receptor for all)
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bitter
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different classes of chemicals--unpleasant, sharp, disagreeable; can be turned off (like vegetables/ you turned it off) pregnant women extra sensitive! (hormones)
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umami
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responds to glutamate, indicates protein (MSG, seaweed, cheese, meat, etc)
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piquancy
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cutaneous pain sense (hot food!)
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distributed coding
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similar patterns of activation for similar flavors
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specificity coding
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specific type of neuron can be added to genome, yields ability to taste certain moleules
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specificity coding in monkeys
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chorda tympani reading shows fibers that respond best to one taste, not others
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detecting odors
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differences lie in how many receptors are present!
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Detection threshold of odors
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measured in ppb; use olfactometer (two puffs, which one has stronger scent?)
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difference threshold
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about 11%; depends on odorant and individual
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identifying odors
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discriminate among 100,000 oders; can't label (not enough words!), odor and language processing compete
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recognition threshold
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concentration needed to determine odorant -- 3x intensity to detect!
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pheromones
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not necessarily for realz in people… but it is connected to fight or flight, sex response of animals
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sweat smell
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info about genes; more or less attractive! Male hormone makes women happy; men rate women as attractive when ovulating; tears reduces testosterone
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shape theory
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shape of molecule causes odor? Umm… nope
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distributed code for smell?
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recognition profiles; maybe!
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olfactory structure
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odorant in, across olfactory mucosa, each neuron has many receptors (350 types!), each olfactory neuron has only one type of receptor
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olfactory mucosa
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4 zones with variety of receptors;; types of receptors found in only one zone, odorants activate neurons within particular zone
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glomeruli
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globs in olfactory bulb; specific types of neurons synaps with one or two glomeruli
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lateral inhibition
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glomeruli have interconnections; MAY use lateral discrimination to enhance odor discrimination
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beyond the olfactory bulb
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neuron --> glomeruli --> piriform (primary olfactory cortex), secondary (orbitofrontal), amygdala!
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chemoctopic representation
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on olfactory bulb only! Not in piriform cortex
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piriform cortex
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learns odor patterns by associating neurons
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individual differences in olfaction
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females have more sensitive olfaction; ability to detect declines with age
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babies
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they can smell and discriminate odors
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smell and memory
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closely tied to amygdala and or hippocampus - stimulates recall
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flavor
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combination of smell, taste, piquancy, temperature, texture, etc
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flavor and smell
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odor stimuli ascend to olfactory mucose through retronasal route
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OFC (orbitofrontal cortex)
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taste and smell combined in OFC, also receives input from what pathway and S1 (taste and smell, taste and vision - multimodal neurons) ASSOCIATED WITH CRAVINGS
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