Tympanometry

The basic principles essential for interpreting two-component, multiple frequency tympanograms first are reviewed. These principles then are applied to an analysis of tympanometric shape (conductance, susceptance, and admittance tympanograms) as a function of probe frequency in subjects with normal middle ear transmission systems. The final section presents tympanometric data from patients with confirmed middle ear pathologies that produce an increase in resonant frequency (e.g., middle ear effusion, otosclerosis, ossicular adhesions, and tympanic membrane retraction) or a decrease in resonant frequency (e.g., otitis externa, serous otitis media, tympanic membrane pathology, and ossicular discontinuity). The advantages and disadvantages of a particular probe frequency and/or admittance component are illustrated with individual cases. The cases further demonstrate that the same tympanometric pattern can be recorded from ears with different pathologies (e.g., tympanic membrane perforation with cholesteatoma, tympanic membrane retraction, ossicular adhesions, and middle ear effusion), and conversely, that the same pathology can result in different tympanometric shapes (e.g., tympanic membrane perforation, middle ear effusion, and otosclerosis). Caution, therefore, must be exercised in ascribing a tympanometric abnormality to a specific middle ear lesion.     

听力正常新生儿1000Hz声导抗分析

目的 分析通过耳声发射(OAE)听力筛查正常新生儿1000 Hz声导抗测试的特点,为新生儿听力筛查及新生儿中耳功能的评估提供参考依据.方法 采用GSI-70型自动耳声发射听力筛查仪对新生儿进行听力筛查,将双耳通过OAE听力筛查的正常新生儿按照纳入标准选为研究对象,共650例(1300耳),然后采用GSI TympStar VersionⅡ中耳分析仪对该研究对象进行中耳功能测试,收集探测音为1000 Hz的鼓室导抗图及其相关指标,对图形进行分型并计算各指标的95％医学参考值范围.结果 将纳入的1300耳的鼓室导抗图分类,其中1Y1B1G型732耳(占56.3％)、1Y3B1G型145耳(占11.2％)、0Y0B0G型269耳(占20.7％)、其他154耳(占11.8％).其中声导纳图Y中单峰型有967耳,计算单峰型声导纳图Y各指标的95％医学参考值范围,其中鼓室图峰压(tympanometric peak pressure,Tpp)为- 55.0～180.0 daPa、峰补偿静态声导纳值(peak compensated static acoustic admittance,Peak Ytm)为0.03 ～1.18 mmHo、鼓室图宽度(tympanometric width,TW)为70.0～230.0 daPa.结论 通过OAE听力筛查的正常新生儿1000 Hz探测音的声导纳图Y以单峰型为主.1000 Hz探测音的单峰型声导纳图Y的Tpp、Peak Ytm、TW的95％医学参考值范围可作为新生儿听力筛查及新生儿中耳功能评估时的参考依据.     

正常新生儿226Hz及1000Hz探测音鼓室导抗测试

探讨通过瞬态诱发耳声发射(TEOAE)筛查的正常新生儿低频（226Hz）及高频（1000Hz）探测音鼓室导抗图的特点、获得峰声导纳值等指标的正常值范围,为临床新生儿及婴幼儿中耳功能评估和诊断提供依据。方法采用中耳分析仪（GSI-33型）对足月顺产,并通过TEOAE筛查的正常新生儿分别进行低、高频探测音下的鼓室导抗测试,分析鼓室导抗图形态特征并对峰声导纳值等重要数据进行统计。结果在100例首次双耳通过TEOAE筛查的新生儿鼓室导抗测试中,低频鼓室导抗图以双峰型为主（占96%）,高频鼓室导抗图以单峰型为主（占90%）;低频探测音鼓室导抗图为双峰型而其高频探测音鼓室导抗图为单峰型的有174耳（占总耳数87%）;低频及高频探测音鼓室导抗图均为单峰型的仅有6耳（占总耳数3%）。结论正常新生儿低频探测音鼓室导抗图以双峰型为主,高频探测音鼓室导抗图以单峰型为主,应将两者结合来对新生儿及婴幼儿中耳功能进行评估;所获得相应的峰声导纳值、峰声导纳值处外耳道压力、外耳道容积等指标的正常值可以用于初步评估新生儿中耳功能状态。     

Tympanometric and acoustic-reflex studies in neonates

Tympanograms and acoustic reflexes for a broadband noise and for a 1000-Hz tone were measured in normal neonates. Notched tympanograms were typical of neonatal ears for a 220-Hz probe tone. A single-peaked tympanogram was most characteristic for a probe frequency of 660 Hz. Ipsilateral and contralateral acoustic reflexes were present more frequently for a 660-Hz probe tone compared to a 220-Hz probe tone, but acoustic-reflex thresholds were not significantly different between probe tones. As with adults, acoustic-reflex thresholds for the noise were significantly lower than for the tone, and ipsilateral reflex thresholds were lower than contralateral reflex thresholds. Reliability of acoustic-reflex and tympanometric measures was high. Age change from 2 to 4 days had no significant effect on tympanometric or acoustic-reflex characteristics. There was no apparent relation between tympanometric pattern and acoustic-reflex characteristics.     

Test-retest reliability in tympanometry.

Test-retest reliability for tympanometric measures was evaluated across five sessions in 20 subjects with normal hearing and normal middle-ear function. Tympanograms were obtained on each ear for probe frequencies of 226, 678, and 1000 Hz using both ascending and descending directions of pressure change. Across all conditions, the tympanometric measure that consistently demonstrated the highest test-retest reliability was compensated static acoustic admittance. Test-retest correlations for peak compensated static acoustic admittance measures were higher than those for ambient measures across all probe frequencies and both directions of pressure change; the differences in correlations for peak and ambient measures, however, reached significance only for 226-Hz conditions. Across-session correlations for tympanogram width did not differ significantly for measures referenced to the lowest tympanogram tail and those referenced to +200 daPa.     

Tympanometric norms for Chinese young adults

OBJECTIVE: To obtain tympanometric norms in Southern Chinese young adult population and compare the results with data obtained for a Caucasian population. DESIGN: Ear canal volume (Vea), tympanometric compensated static acoustic admittance (Peak Ytm), tympanometric width (TW) and tympanometric peak pressure (TPP) were obtained on 100 Southern Chinese young adults. Results were compared with findings from Roup et al. (1998). Inter-tester reliability was established. RESULTS: Compared with the results obtained by Roup et al. (1998) on non-Hispanic Caucasian population, Southern Chinese subjects were found to have lower Peak Ytm, wider TW and more positive TPP values. No gender difference was noted for Peak Ytm, TW and TPP values in Chinese subjects. Inter-tester reliability was good. CONCLUSION: The tympanometric norms obtained in this study are recommended when evaluating middle ear function among Southern Chinese young adults.     

Simulation of pathological high impedance tympanograms

The Vanhuyse, Creten, and Van Camp (1975) model for analyzing high frequency tympanograms predicts the shapes of conductance, susceptance, and admittance tympanograms from the relationship between resistance and reactance tympanograms at the tympanic membrane. This model has been applied primarily to low impedance middle-ear pathologies but has not been applied extensively to the more commonly occurring high impedance pathologies. The purpose of this study was to extend the Vanhuyse et al. (1975) model to high impedance pathologies and to identify tympanometric parameters associated with otosclerosis, secretory otitis media, and lateral ossicular fixation. Data from previous experiments on the shape and absolute values of resistance and reactance tympanograms were used to calculate 678-Hz admittance tympanograms that were unique to each of the three high impedance pathologies. Guidelines for differentiating among the middle-ear pathologies on the basis of high frequency tympanometric shapes are presented.     

Mechanoacoustic properties of the tympanic membrane: a study on isolated Mongolian gerbil temporal bones.

In order to study the mechanical properties of the tympanic membrane in diseased ears, we have designed and evaluated an experimental tympanometric model. Isolated temporal bones of healthy Mongolian gerbils were studied with a Grason-Stadler 1723 typanometer in two-component admittance measurements with probe tones of 220 and 660 Hz. The normal tympanometric curve is described, and the validity and reproducibility of the model are assessed. The morphology of the gerbil tympanic membrane is described and compared with those of other species. Various alterations were produced in the middle ear, and it was found that tympanometry showed high sensitivity for tympanic membrane stiffness but not for mass changes. The condition of the pars flaccida did not significantly influence admittance, which was also resistant to osmotic challenge to the membrane. Ossicular chain disruption caused an increased admittance, whereas malleus fixation, without affecting the tympanic membrane itself, caused a pronounced reduction. The tympanometric patterns during tympanic membrane mass increase, and with hypertrophic myringeal scars and perforations were also determined. We conclude that tympanometry in the in vitro middle ear of gerbils offers possibilities for studying changes of the tympanic membrane physiology in disease.     

High-frequency (1000 Hz) tympanometry in normal neonates

The characteristics of high frequency (1000 Hz) acoustic admittance results obtained from normal neonates were described in this study. Participants were 170 healthy neonates (96 boys and 74 girls) aged between 1 and 6 days (mean = 3.26 days, SD = 0.92). Transient evoked otoacoustic emissions (TEOAEs), and 226 Hz and 1000 Hz probe tone tympanograms were obtained from the participants using a Madsen Capella OAE/middle ear analyser. The results showed that of the 170 neonates, 34 were not successfully tested in both ears, 14 failed the TEOAE screen in one or both ears, and 122 (70 boys, 52 girls) passed the TEOAE screen in both ears and also maintained an acceptable probe seal during tympanometry. The 1000 Hz tympanometric data for the 122 neonates (244 ears) showed a single-peaked tympanogram in 225 ears (92.2%), a flat-sloping tympanogram in 14 ears (5.7%), a double-peaked tympanogram in 3 ears (1.2%) and other unusual shapes in 2 ears (0.8%). There was a significant ear effect, with right ears showing significantly higher mean peak compensated static admittance and tympanometric width, but lower mean acoustic admittance at +200 daPa and gradient than left ears. No significant gender effects or its interaction with ear were found. The normative tympanometric data derived from this cohort may serve as a guide for detecting middle ear dysfunction in neonates.     

Standard and multifrequency tympanometric norms for Caucasian and Chinese young adults

OBJECTIVE: This study examined differences between a group of normal-hearing Caucasian and Chinese young adults on six tympanometric parameters. The goal of this study was to determine if the Chinese group had different low and multifrequency tympanometry results than the Caucasian group. DESIGN: There were a total of 159 subjects (303 ears) between the ages of 18 and 34 years, with 76 subjects in the Caucasian group and 83 subjects in the Chinese group. Tympanometric data were gathered on a clinical immittance machine, the Virtual 310 equipped with a high frequency option. Four of the parameters-static admittance (SA), tympanometric width (TW), tympanometric peak pressure (TPP), and ear-canal volume (ECV)-were measured automatically at a standard 226 Hz frequency. The remaining two parameters-resonant frequency (RF) and SA up to 1,200 Hz-were measured by multifrequency, multicomponent tympanometry, using a mathematical approach. RESULTS: The Chinese group had significantly lower SA, wider TW, more positive TPP, and lower ECV than their Caucasian counterparts. The parameter of SA up to 1,200 Hz showed a significant group effect (Caucasian versus Chinese) until 900 Hz in the male group and up to 1,120 Hz in the female group. The Chinese group had significantly higher RF than the Caucasian group. Once the effect of body size was compensated by adjusting for the ear canal and the middle ear volumes, the differences observed between the Caucasian and the Chinese groups were no longer significant for tympanometric parameters obtained at standard probe tone frequency of 226 Hz; however, the effect was still significant for SA obtained at higher probe tone frequencies (560, 630, 710, 800, and 900 Hz) and for RF. Applying the Caucasian norms to a group of mainly Caucasian adults with surgically confirmed otosclerosis resulted in improved overall test performance when compared with the combined Caucasian and Chinese norms and the Chinese only norms. CONCLUSIONS: It seems that the body size plays a crucial factor in the observed differences between the Caucasian group and Chinese groups at a standard probe tone frequency of 226 Hz; however, other mechano-acoustical properties of the middle ear may contribute to these differences at higher probe tone frequencies. Findings of this study suggest that further research is needed to investigate the effects of body size on immittance measures with other ethnic groups. In the meantime, overall test performance may be improved by using a more homogenous norm when testing the Caucasian or Chinese individuals.     

Evaluation of middle ear function in young children: clinical guidelines for the use of 226- and 1,000-Hz tympanometry.

HYPOTHESIS: The aims of the study were to evaluate tympanometry with regard to age and classification system using two probe-tone frequencies and to provide clinical guidelines. METHODS: Six subject groups were included in the evaluation: (1) neonatal intensive care unit babies, (2) children younger than 3 months, (3) children 3 to 6 months old, (4) children 6 to 9 months old, (5) children 9 to 32 months old, and (6) adults. Hearing of all subjects was screened by means of auditory brainstem responses, transient-evoked otoacoustic emissions, or behavioral audiometry. Tympanograms, recorded with probe-tone frequencies of 226 and 1,000 Hz, were classified according to shape and middle ear pressure. Additionally, 1,000-Hz tympanograms were classified based on the Vanhuyse model of tympanometric shapes. Furthermore, tympanometric parameters equivalent ear canal volume, admittance value at +200 daPa, middle ear admittance, tympanometric peak pressure, and tympanometric width were calculated for each tympanogram. RESULTS: For clinical purposes, the visual admittance classification system was more suitable than the Vanhuyse model. Furthermore, in children younger than the age of 3 months, 1,000-Hz tympanometry was easier to interpret and more reliable than 226-Hz tympanometry. From the age of 9 months, 226-Hz tympanometry was more appropriate. In children between 3 and 9 months, the reliability of tympanometry was independent of probe-tone frequency. A two-stage evaluation with a 1,000- to 226-Hz tympanometry sequence was preferred because this reduced the total number of tests. CONCLUSION: The current study provides normative data and age-related guidelines for the use of tympanometry in clinical practice. These results have led to a successful implementation of 1,000-Hz tympanometry in neonatal hearing assessment.     

Tympanometric changes at 226 Hz and 678 Hz across 10 trials and for two directions of ear canal pressure change

The influence that repeated tympanometric trials have on the aural-acoustic admittance characteristics of the middle-ear transmission system was studied in 24 young adults. The 226-Hz and 678-Hz data were generated by concurrently digitizing the conductance and admittance tympanograms at 25 daPa/s for both ascending and descending pressure directions. Ten successive trials for each frequency and direction of pressure change were made. Changes in admittance corrected for ear canal volume across the 10 tympanometric trials were computed. The results demonstrated that generally admittance increases as the number of trials increases. For many subjects, the complexity of the tympanometric configuration also increases across trials. The results from eight subjects with single-peaked 678-Hz tympanograms were compared with the results from eight subjects with notched 678-Hz tympanograms to explain the mean decrease in susceptance across tympanometric trials. Finally, the pressure peak locations of the conductance, susceptance, and admittance tympanograms were evaluated and are discussed. The effects that differences in peak pressure location have on the computed static admittance values are presented.     

Middle ear volume and pressure effects on tympanometric middle ear pressure determination: model experiments with special reference to secretory otitis media

Objective: Middle ear pressure (P(m)) measured by tympanometry has revealed high negative values in patients with secretory otitis media (SOM) in contrast to direct measurement. This may be explained by errors in tympanometry caused by volume displacement of the tympanic membrane (TM) affecting the volume of the middle ear (V(m)) and the P(m) according to Boyle's Law. Such errors are susceptible to the size of V(m). Methods: A realistic middle ear model based on previous clinical studies of normal pressure-volume relations of the middle ear system (MES) was constructed. In this model non-linear behaviour and hysteresis of the MES was imitated and P(m) as well as V(m) could be controlled. Results: Tympanometrically estimated P(m) decreased on average 38 daPa, when V(m) was changed from 21 to 1 cm(3). The decrease was most pronounced, when V(m) became smaller than 5 cm(3). Moreover, tympanometry showed a linear numerical overestimation of P(m) by a factor 2.31 compared with model P(m). Conclusion: A curve fit was derived describing the tympanometric P(m) as a function of V(m). This demonstrated that tympanometric P(m) approached -infinity daPa, when middle ear volume approached 0 cm(3), which indicates that negative tympanometric recordings and B curves can be found in ears with normal P(m) entirely due to very small V(m)'s. This explains the discrepancy between direct and tympanometric measurements of P(m) in SOM, since the effusion replaces the air filled expandable volume resulting in a very small 'functional' V(m). Numerical overestimation of P(m) by tympanometry was explained by hysteresis, which reflected the viscoelastic properties of the MES. These results question the significance of negative P(m)'s as a pathogenetic factor in SOM.     

Identification of middle ear dysfunction in young children: a comparison of tympanometric screening procedures.

Two acoustic immittance screening procedures were evaluated in conjunction with pneumatic otoscopy, performed by a pediatric otolaryngologist. The subjects were 204 3- and 4-yr-old children from a rural area in eastern North Carolina. Pass-fail criteria were examined using two middle ear screening procedures: (1) a "traditional" procedure based on measures of tympanometric peak pressure and acoustic reflexes, and (2) the tympanometric measures contained within the American Speech-Language-Hearing Association's (ASHA) revised Guidelines for Screening for Hearing Impairment and Middle Ear Disorders. The traditional procedure resulted in low specificity but high sensitivity, whereas ASHA's immittance procedure resulted in high specificity but only moderate sensitivity. The negative predictive value was very high for both procedures; however, positive predictive value was low, especially for the traditional procedure. Advantages and disadvantages of the two procedures and future research needs are discussed.     

Parameters of normality in multifrequency tympanometry

Multifrequency tympanometry studies consist of tympanography using probe tone frequencies ranging from 200 to 2000 Hz, improving the study of acoustic transmission through the tympano-ossicular system because then two components of admittance, conductance and susceptance, can be separated. The resonance frequency is the frequency at which mass and spring elements of the middle ear cancel each other out, leaving only the friction component. This measurement has been found to be more sensitive to the presence of pathologies that affect the tympano-ossicular system, such as otosclerosis and rheumatoid arthritis. It is necessary to know normal pattents of tympanometric parameters to improve the study of these diseases. Multifrequency tympanometry performed on 136 patients, 91 women and 45 men, age range 11-78 years. The mean resonant frequency of the middle ear was 1132.33 Hz, mean static admittance 0.76 dapa, and mean tympanometric amplitude 94.31 mmhos ac. Age showed no systematic effect of age on any of these measures in this population, and no significant association was found between static admittance or tympanometric amplitude and resonance frequency.     

Developmental changes in multifrequency tympanograms

The normal maturational course of tympanometric shape, static aural acoustic admittance and ear canal wall characteristics were investigated in healthy infants, who were followed at various time intervals in the first 4 months of life. Susceptance and conductance tympanograms were recorded from both ears of each subject at four probe frequencies or more. In addition, quantitative pneumatic otoscopy was performed utilizing air pressure changes of the same magnitude as those typically used in tympanometry. Results for the group were an increase in admittance magnitude with increasing age at frequencies above 226 Hz. Admittance phase angle increased with age at all frequencies, indicating a growing contribution of compliant elements in the first 4 months of life. The course of development of input admittance at the tympanic membrane differed among individual infants. Otoscopic findings indicated that external ear canal differences cannot completely account for tympanometric differences between young infants and adults.     

Comparison of tympanometry and otomicroscopy during healing of otitis media

One hundred ears in 50 children with acute otitis media during healing were examined with tympanometry and the objective measures were compared with the subjective evaluation of otomicroscopy by four otolaryngologists independently. Tympanometric findings could more often correctly suggest reduced tympanic membrane mobility than did otomicroscopy, but both methods gave an equally good indication of middle ear effusion. However, otomicroscopy was necessary when evaluating the colour and the appearance of the tympanic membrane and revealed middle ear effusion in a few cases with 'normal' tympanometry. As a rule: normal tympanometry (Jerger type A) was closely correlated with a normal tympanic membrane and a normal middle ear without effusion; pathological tympanometry (Jerger type B) was accompanied by middle ear effusion and needed follow-up; ears with tympanometric pressure more negative than -150 mmH2O but more positive than a flat curve needed otomicroscopy to identify middle ear effusion.     

Screening Tympanometry: Criteria for Medical Referral

Tympanograms were obtained from normal preschool and adult subjects with a prototype hand-held tympanometer to obtain normative values for four tympanometric variables: static admittance, equivalent ear canal volume, tympanometric peak pressure, and gradient. Effects of age group, sex, and pump speed (200 or 400 daPa/s) were determined. The results were incorporated into a four-part screening protocol (history, visual inspection, audiometry, and tympanometry) designed to reduce the excessive error rates associated with screening strategies that rely exclusively on tympanometry.     

Screening tympanometry: criteria for medical referral

Tympanograms were obtained from normal preschool and adult subjects with a prototype hand-held tympanometer to obtain normative values for four tympanometric variables: static admittance, equivalent ear canal volume, tympanometric peak pressure, and gradient. Effects of age group, sex, and pump speed (200 or 400 daPa/s) were determined. The results were incorporated into a four-part screening protocol (history, visual inspection, audiometry, and tympanometry) designed to reduce the excessive error rates associated with screening strategies that rely exclusively on tympanometry.     

International Organization of Audiology (Table 1)

Some principles underlying acoustic impedance measurements in the ear canal and their evaluation are reviewed. The following topics are included: some methods of measurement, useful frequency range, the middle-ear system, impedance characteristics of normal and some pathological ears, and the relation between the impedance and tympanometric results. Advantages and disadvantages of measurements with an acoustic bridge and parallel probe tubes are contrasted and the same is done for tympanometry versus static impedance measurements. The relation between tympanograms and static impedance data referred to the tympanic membrane is illustrated by means of a semihypothetical example. The example suggests that a probe frequency around 700 Hz is more informative in tympanometry than a probe frequency of 220 Hz.