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otitis media with effusion is a common pediatric disease and is considered the most common cause of hearing impairment among children .
diagnosis is mainly based on pneumatic otoscopy , pure - tone audiometry , and tympanometry .
tympanometry is an objective technique that can detect abnormal middle - ear function consistent with the presence of fluid in the middle - ear cavity .
transiently evoked otoacoustic emissions ( teoaes ) are a diagnostic method widely used during the past decade to study cochlear function , in a noninvasive and objective manner .
usually , teoaes are present in people who have normal cochlear function and a healthy middle ear .
although extensive experience from the use of teoaes in widespread neonatal hearing screening has been gained , little data has been gathered from the population of preschool and school - aged children . because otoacoustic emissions are transmitted from the cochlea to the external ear canal via the middle ear
, middle - ear effusion reduces measured emission amplitudes and sometimes eliminates the response entirely .
the aim of this study was to evaluate teoaes in the diagnosis of otitis media with effusion in comparison with tympanometry .
twenty - one of them were male and 17 female , ranging in age from 4 to 15 years , with a mean age of 8.3 years .
both patients and controls underwent clinical otologic and audiological evaluation including medical history , pneumatic otoscopy , tympanometry , and standard pure - tone audiometry .
the diagnosis of otitis media with effusion was established when findings in at least three of them were positive .
this was used as the gold standard for the comparison of the diagnostic accuracy of teoaes , tympanometry , or their combination .
conventional pure - tone audiometry was conducted in a standard sound proof booth , using a two - channel amplaid 455 audiometer and earphones .
standard audiometric procedures were applied and the pure - tone thresholds of each ear at frequencies of 0.25 , 0.5 , 1 , 2 , 3 , 4 , and 8  khz were measured .
subjects were considered to have a hearing loss if any threshold between 250 and 8000  hz exceeded 20  db  hl . when air conduction thresholds were out of normal hearing range , bone conduction thresholds were obtained .
standard single - frequency tympanometry was performed with an amplaid 770 clinical admittance meter , using a single frequency 85  db spl ( sound pressure level ) tone set at 226  hz . the range of ear canal pressure was + 400 to 600  dapa .
the american speech - language - hearing association   guidelines were used to determine if a tympanogram was considered abnormal : ( 1 ) static admittance less than 0.3  mmho ; ( 2 ) an equivalent ear canal volume greater than 1.0  cm when accompanied by a flat tympanogram ; ( 3 ) tympanometric width greater than 200  dapa .
teoaes were further performed in all patients and controls , using a dp echoport ilo 292 otodynamics analyzer connected to a portable personal computer .
the acoustical stimulation , the data recording , and the data analysis were produced automatically with the aid of this system .
testing was performed in a sound - treated room using a standard ilo adult probe with disposable tips .
. the nonlinear method of recording was used , allowing the phase - locked cochlear component of the response to be measured .
the recording bandwidth was set between 0.75 to 5  khz , stimulus intensity was approximately 80  db , and repetition rate was 50 stimuli / sec .
the numbers of responses accepted and rejected by artefact rejection were displayed and updated during averaging .
the  pass  criteria were signal - to - noise ratio 6  db , in four of five 1/2 octave frequency bands at 1 , 1.5 , 2 , 3 , and 4  khz .
however , pneumatic otoscopy , tympanometry , and teoaes were performed to both of them successfully , and the diagnosis of otitis media with effusion was established .
mean pure - tone thresholds exceeded 20  db  hl for the lower and middle frequencies in the group of children with otitis media with effusion , whereas mean values lower than 20  db  hl were found in the control group across all the examined frequencies ( table 1 ) . in 72 ears ( 94.7% ) of the group of patients
the tympanograms were abnormal and in the remaining 4 ( 5.3% ) they were normal . in 70 ears ( 87.5% ) of the control group tympanograms
were normal , whereas in the remaining 10 ears ( 12.5% ) tympanograms were abnormal .
in table 2 , the results for sensitivity , specificity , positive predictive value , and negative predictive value , with their corresponding 95% confidence intervals , are shown . in 51 ears of the patients ( 67.1% ) otoacoustic emissions
the mean emission amplitude was reduced , compared to the mean value of the control group ( table 1 ) . in 68 of the 80 ears of controls clear
comparison of signal - to - noise ratios by independent sample t - test between the two groups showed statistically significant differences . in all cases
the values of the patients were lower than the mean value of the controls . in this comparison
the sensitivity of teoaes was 67.1% and its specificity was 85% ( table 2 ) .
combination of teoaes and tympanometry yielded sensitivity 98.6% and specificity 92.5% , improving further diagnostic accuracy ( table 2 ) .
the screening test efficiency values ( overall number of true positives and true negatives divided by the total number of ears tested ) for teoaes , tympanometry , and their combination were , respectively , 76.2% , 91% , and 95.5% .
teoaes are a valuable screening tool for hearing impairment , although neither information about the degree or configuration of hearing loss is provided , nor is differential diagnosis between sensorineural and conductive hearing loss possible .
teoaes are transmitted from the cochlea through the ossicles and tympanic membrane and measured in the external ear canal .
therefore , any middle - ear or outer - ear disorder can practically interfere with transiently evoked otoacoustic emission transmission .
it has been reported that artificial manipulation of the middle - ear compliance causes a decrease in the response levels of the otoacoustic emissions .
.   found that a type b tympanogram precluded recording of transiently evoked otoacoustic emissions .
even the presence of negative tympanometric peak pressure has been found to lower the level of teoaes , by approximately 4  db across 1000 to 4000  hz .
also , owens et al .   reported that in ears with type b and c tympanograms transiently evoked otoacoustic emissions were absent or had reduced amplitudes and concluded that , in general , the use of teoaes is contraindicated in the presence of any middle - ear disorder .
furthermore , choi et al .   reported that middle - ear effusion or a type b of tympanogram impeded measurement of transiently evoked otoacoustic emissions , whereas type a of tympanogram was found to be associated with present emissions . however , hall iii et al .  
proposed that otoacoustic emission testing should be performed even in the presence of middle - ear disease .
koike and wetmore   found that the status of the middle ear greatly affected transiently evoked otoacoustic emission measures , which was most significant with flat tympanograms , mainly indicative of reduced tympanic membrane mobility and the presence of middle - ear effusion .
in several reports , high failure rates of teoaes in cases with flat tympanograms were found .
ho et al .   reported failure rates approaching 71 - 72% in ears with middle - ear effusion and abnormal tympanograms .
these authors found good agreement between tympanometry failure and transiently evoked otoacoustic emission failure for the 3- to 5-year - old group of children .
similar rates were found in another report of transiently evoked otoacoustic emission measurements , and our rate of approximately 67% failure is in accordance with them . in most of the previously mentioned reports
fortunately , quantitive analysis is now possible and objective criteria may be used , as in the present study .
have also used teoaes as a hearing screening tool in children with ome , before and after surgery . according to these authors ,
preoperative teoaes were absent in 93.5% of the ears , but were significantly improved postoperatively . when applying tympanometry and teoaes in hearing screening , the sensitivity and specificity of both tests should be considered .
the problem in such studies is the absence of a gold standard , as would be the findings of myringotomy in the examined ears .
however , this is not possible in most cases , and several authors have used tympanometry as the gold standard , due to its high sensitivity to middle - ear disorders .
taylor and brooks   obtained by this method 60% sensitivity and 91% specificity of teoaes compared to tympanometry .
recently , liwa et al .   combined three diagnostic methods , automated 4-frequency audiometry , toeaes and tympanometry , in hearing screening of school children .
the authors used conventional tone audiometry as the reference and found high specificity and low sensitivity values for all the tests , but combination of tympanometry and teoaes yielded 60% sensitivity and 94% specificity , whereas addition of automated 4-frequency audiometry further improved sensitivity to 70% . in our study , we used the combination of positive history , positive otoscopic appearance by pneumatic otoscopy , abnormal tympanographic findings , and elevated threshold in pure - tone audiometry as a gold standard to establish diagnosis . according to these , the sensitivity of tympanometry was as high as 96% and its specificity was 85% . when calculating the sensitivity of teoaes according to the  pass  criterion , a rate of 67%
was obtained , whereas specificity approached 85% . however , in the remaining ears which obtained the 
pass  criterion , transiently evoked otoacoustic emission measurements were lower than controls , at a statistically significant level .
it appears , thus , that the sensitivity of teoaes in otitis media with effusion is high , whenever absolute values of teaoe measurements are considered and not only a 
specificity is lower , because teoaes are also influenced by inner - ear disease , although this is not quite common in the age group of our study .
finally , a comment on pure - tone thresholds in standard audiometry should be made . in several reports ,
mean pure - tone thresholds between 15 and 20  db  hl have been found . in our study
mean thresholds were approximately 2025  db  hl in the standard frequencies of 0.5 , 1 , 2 and 3  khz .
it appears , thus , that an audiometric criterion of 20  db would be appropriate to separate normal ears from ears with absent or reduced transiently evoked otoacoustic emissions .
from this study , it may be concluded that teoaes should be included in the diagnostic workup of otitis media with effusion .
their sensitivity in diagnosing middle - ear disease is high when quantitive measures are used , whereas their specificity is lower , because abnormal results may also be found in cases with inner - ear disease .
for this reason , teoaes should always be used along with tympanometry , because a more meaningful interpretation of transiently evoked otoacoustic emission measures in conjunction with tympanometry results is possible .
introduction . otitis media with effusion is a common pediatric disease whose diagnosis is based on pneumatic otoscopy , pure - tone audiometry , and tympanometry . the aim of this study was to evaluate transiently evoked otoacoustic emissions in the diagnosis of otitis media with effusion as compared to tympanometry . 
 patients and methods . 
 38 children with bilateral otitis media with effusion were studied . 
 40 normal children of similar age and sex were used as controls . 
 all subjects underwent pneumatic otoscopy , standard pure - tone audiometry , tympanometry , and transiently evoked otoacoustic emissions . results . in the group of children with bilateral otitis media , 
 transiently evoked otoacoustic emissions were absent in 51 ears ( 67% ) . in the remaining 25 ears ( 33% ) 
 the mean emission amplitude was reduced , as compared to the mean value of the control group . 
 conclusions . 
 transiently evoked otoacoustic emissions should be included in the diagnostic workup of otitis media with effusion because it is a fast , reliable , and objective test . 
 transiently evoked otoacoustic emissions should always be used in conjunction with tympanometry , because a more meaningful interpretation of transiently evoked otoacoustic emissions measures is possible .