CSE 115: TEST 4
62 Cards in this Set
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Auditory map of space
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Frequency to place map-no direct map of sound source to cochlea. Acoustic cues in 2 ears
TIME AND INTENSITY CUES
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Lord Rayleigh_Front-Back Confusion
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Cues reach ear at exact same time and intensity front and back-diotic stimuli (same)
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Circle of Identity
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Same binaural intensity. Cone of confusion
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Intensity diff is greater for ____ freq
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HIGH (doesn't bend around head as much)
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ILD-Interaural level diff
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diff btwn levels of sound-bigger head shadow at high freq
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ILD is almost zero when
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Wavelength of sound is 4x circumfrence (160Hz)
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Helmholtz WRONG on phase deafness
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the ears DO use time, idiot
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ILD is largest at __degrees for freqs greater than __
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90º at > 1kHz
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Thompson- Phase cues for sound localization
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Amplitude Modulation-can combine and subtract
2 tones slight diff freq=loudness fluctuate and seems to move
phase is important but helmholtz said no
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Raleigh-dichotic experiment
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auditory brain uses phase relationships-diff freq simultaneously become added and seem moving
bigger head shadow effect at high freq
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We can detect time diff as small as __microseconds
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10 microseconds
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Wilson and Myers tube exp
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time and intensity used to localize
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Sound source on median plane=
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no binaural distance=no intensity diff
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ILD max and min summary
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Max intensity diff=10kHz (head shadow)
Min intensity diff=250Hz
Largest at 90º
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Time diff is easier for __freq
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LOW
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Intensity cue best at __freq
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HIGH
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Intensity cue best at __freq
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HIGH
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Intensity cue small at___
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LOW <2kHz freqs
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Intensity localization greatest at___freq
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HIGH
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Intensity localization greatest at___freq
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HIGH
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Errors from using both cues at
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3kHz
phase great for low,
intensity great for high,
error when they come together around 3kHz
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Duplex theory
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Low freq-TIME
High freq-INTENSITY
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Halverson-Sound Lateralization
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Sound feels INSIDE head (headphones)
500Hz at 0º=middle
" at0-180º=middle to R ear
" at 180-360º=middle to L ear
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Laterlization vs Localization
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Localization-loudspeakers outside head
Laterlization-headphones middle of head to each ear
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Yost- Minimum Audible Angle
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Time cues deteriorate from 1400Hz
>1400Hz can no longer do task
PHASE CAN ONLY BE USED UP TO 1400Hz
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Yost and Hafter time diff of later and loca lizations
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laterlization-just noticable phase diff at 1200Hz=12º or 27 microseconds
localization-just noticeable phase diff at 100Hz=3º or 83 microseconds
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Time cues are powerful but only work at low freq
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can use time cues with high freq by using AM
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Onset disparity
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hear sound in 1 ear first think its from there, important for SHORT sound duration
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Offset Disparity
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On at same time, 1 ear goes off later=its the ear that was stimulated last
Up to 6ms to make a disparity
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which is more powerful-onset or offset disparity
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ONSET!
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With LOW freq we mainly use__ cues
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TIME
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With HIGH freq we mainly use__ cues
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INTENSITY
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We confuse time and intensity cues at__kHz
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3kHz
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Precedence Effect
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whichever ear hears the sound source first is where sound is localized
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Masking level difference
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make signals detectable by changing the phase
change one ears phase by 180 you can understand speech in noise, overcomes masking
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Retrocochlear Hearing Loss
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Problem beyond cochlea
Problem is in 8th nerve or cochlear nucleus, superior olivary, inferior colliculus, etc
IdentifiedIdentified with acoustic reflex and rollover
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Manifestations of retrocochlear HL
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rare
sudden onset HL, unilateral SNHL usually
poor speech discrim
dizziness and/or tinn
normal tymp
acoustic reflex absent
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Tests to determine retrocochlear HL
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Puretone air and boneimmittance and acoustic reflexesspeech discrimtone decay-person cannot hear tone for full 60 sec even if louderreflex decay-if reflex, only lasts 10secevoked potentials-ABR delays
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Tumor on Aud nerve-acoustic neuroma
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60sec tone fades away in bad ear before 60 sec
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Decruitment
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Abnormally slow growth of loudness with increasing sound level-found in ACOUSTIC NEUROMA
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Tests for central auditory disorders
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Phonetically Balanced word listsBinaural audiometry using filtered speechMasking level differenceEvoked potentials-ABR
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Rollover effect of phonetic word test
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discrim poor at low intensity, improves, then gets worse-seen with central aud pathology, tumor often contralateral to ear being tested
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Masking Level Difference
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Tone both ears at 0º, binaural noise 180º out of phase= normal listeners thresholds improve 10-15dB
Central lesion=little improvement
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binaural distance difference
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diff between distance sound reaches ears, midline mid saggital medial and horizontal planes
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circle of identity
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binaural distance difference is the same distance to sound source to each ear is equal
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conductive hearing loss
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outer and middle ear. cerumen, disarticulation, colesteatoma
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Tympanogram Types
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Ad=eardrum perforation
As=otosclerosis
C=neg pressure, otitis media
B=flat, fluid in ear, infection
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Degrees of Hearing Loss
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20-40=mild
40-70=moderate
70-90=severe
90-120=profound
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Acoustic reflexes are ___ in retrocochlear HL
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absent or abnormal
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Rollover
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Speech discrim testing, as increase volume, performance gets WORSE-retrococh
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Decruitment
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sound slowly increasing when in reality its faster-retrococh
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cochlear implants take ___weeks to heal
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4-6 weeks
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adult candidates for cochlear implants
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-bilateral SNHL, severe-profound in mid-high freqs, moderate-profound in low freqs
-post-lingual onset of deafness preferred
-small benefit from HAs
-psychologically, motivationally suitable
-no medical contraindications
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child candidates for cochlear implants
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-<2 yrs: profound bilateral SNHL
- >2 yrs: bilat SNHL, severe-profound in low freqs, profound in mid-high freqs
-little or no benefit from HA’s (3-6 mo trial)
-failure to develop simple auditory skills
(<2 yrs)
-no medical contraindications
-enrolled in ora…
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medical contraindications for cochlear implants
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-congenital absence of cochlea and/or AN
-lesions of auditory nerve or CANS
-active middle ear disease
-surgical risks
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Raleigh-optimized wavelengths to make shadow effect=0
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Bigger shadow effect at high freq
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Harris&Sergeant-minimum detectable change on horizontal plane
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Tones-binuaral better than monaural
Noise-both binaural and monaural equal because pinna alters spectrum of noise for change in position
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Stevens and Newman-localization errors
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Localization error greatest at mid frequencies
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Mills-minimum audible angle
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detects change in location of sound source. Minimum audible angle is smallest when sound source is directly in front (0º)
Poorest when source moves to side of head (60º)
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Formula for NEAR sound source
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d=K*2B
K=radius of head
B=angle of midline
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CSE 115: TEST 1