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  1. three types of oaes
    • oae=otoacoustic emissions
    • 1. transient oae 
    • 2. spontaneous oae
    • 3. distortion product oae
  2. who discovered oaes
    • dr. david kemp in 1977
    • set the stage for dramatic changes in our understanding of how the auditory system is able to respond to the vanishingly small energy levels that are required to reach thresh of perception of humans
    • signal checks hair cell and how much they are picking up
  3. what is an oae
    • any sound that is produced by the cochlea and detected in the ear canal
    • 1. temporal and spectral characteristics of emission will reflect the region of the cochlear that produces it
    •     -clicks-broad freq range
    •     -tones-specific freq of tone burst
    • 2. emissions can be surppressed or reduced in amp by presentation of ipsilateral or contralateral stimuli
    • 3. emission properties are altered in the presence of slight hearing loss and the probability of detecting emissions in the freq region when hearing loss exceeds 30 db is low
    •      -is loss is greater than 30 db you will not get an emission because whatever is there is being depressed
    • 4. emissions extracted from background noise in the external ear canal by sampling the sound in the ear canal to develop an average time waveform or a spectral analysis or a combo of temporal and spectral averaging techniques
  4. SOAEs
    • spontaneous emissions
    • occur without intentional stimulation of the ear
    • vary narrow bands (less than 30 hz) of freqs recorded in the external ear canal in the absence of an evoking acoustic signal
  5. SOAE characteristics
    • more common in females than in males
    • less common and fewer in number in person over 50
    • comparable prevalence in infants, children and young adults
    • freqs are stable for long periods of times
    • amp may fluctuate over time
    • most often present in the 1 and 2 hz region
    • multiple soae freqs are common in individuals 
    • if present in an individual, likely to be present in both ears
    • no positive association between soae and tinnitus
    • not consistent with objective tinnitus
  6. TEOAE
    • transient oto emissions
    • occur during brief broad-spectrum click
    • accomplished using time-synchronous averaging
    • averaging reduces the amount of noise in the tracing 
    • two waveforms superimposed on each other, stored in two separate buffers
    • put in on purpose
  7. Characteristics of TEOAEs
    • evaluated in terms of amp, percentage reporducibility, and amp/noise (SNR)
    • AMP=level of oae, usually expressed at spl (SOUND PRESSURE LEVEL)
    • percentage reproducibilty=how well the two TEOAE traces correlate with one another
    • SNR=ratio of the amp of the TEOAE to the amp of the noise expressed in db
    • age effect on threshs
    • 25 db
    • right ears have larger TEOAEs than left ears
    • females ten to have larger TEOAEs than men
    • they are very noise sensitive
  8. DPOAEs
    • distortion product otoacoustic emissions
    • output of energy at freqs other than those contained in the input stimulus
    • measured simultaneously with two pure tone stimuli
    • f1 and f2, l1 and l2
    • occure at predictable freqs that are mathematically related tothe freqs of the primaries
  9. DPOAE characteristics
    • might be considered present if its amp is 6 db or more above the level of the surrounding noise floor or it its amp exceeds two standard deviation above the mean noise
    • change with development
    • can be present at 35-40 db hearing loss
    • no significant differences between ears
    • no diff between males and fems
    • used for newborn hearing screening and ototoxicity screening
    • not as sensitive to noise better responses
  10. oaes have to accompany what tests
    behavior test so that you have something to compare them to
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2014-03-01 03:04:22
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