High- and Low-Frequency Probe Tone Tympanometry in Chinese Infants

Objective To assess the utility of low- and high-frequency tympanometry in the diagnosis of middle ear dysfunction in Chinese infants. Methods Tympanograms were obtained with 226 Hz, 678 Hz and 1000 Hz probe tones from infants aged 5-25 weeks with normal auditory brainstem responses (ABRs)(15 infants,30 ears) and withprolonged wave Ⅰ latencies(17 infants, 20 ears), suggesting middle ear dysfunction, using a GSI Tympstar middle ear analyzer Version Ⅱ. Results The single-peaked tympanogram was the most characteristic type in both groups and seen in 25 ears (83.3%) in the normal ABR group and in 18 ears (90%) in the delayed wave Ⅰ group, respectively. The peak pressure, peak compensated static acoustic admittance and gradient of 226 Hz tympanometry were of no significant differences between the two groups. The 678 Hz tympanograms of admittance, susceptance and conductance demonstrated non-peak, single-, double- and tri-peaked patterns in both groups. The agreement between ABRs and 678 Hz tympanograms of admittance,susceptance and conductance were 70.0%, 58.0% and 64.0%(kappa=0.324, 0.234 and 0.118) respectively. For 1000 Hz probe tone, admittance,susceptance and conductance tympanograms showed single peaked patterns in 28 (93.3%), 25 (83.3%) and 26 (86.7%) of the 30 normal ears. Admittance, susceptance and conductance tympanograms using the 1000 Hz probe tone were flat in 15 (75%), 17(85%) and 13 (65%) of the ears in infants with prolonged wave Ⅰ latencies. For 1000 Hz admittance, susceptance and conductance Tympanograms, the agreement between tympanometry and ABR results were 90.0%, 92.0% and 86.0% with kappa at 0.783, 0.831 and 0.690, respectively. Conclusion 1000 Hz probe tone tympanometry is a promising middle ear function test for infants of 1-6 months age, while 226 Hz and 678 Hz probe tones are less efficient in detecting middle ear dysfunction in infants.     

足月正常新生儿多频探测音鼓室声导抗正常值测定

目的：探讨正常新生儿多频探测音鼓室声导抗图的图型、声导纳值、声纳值和声导值的正常范围。方法：使用GSI-33中耳分析仪,对足月顺产并通过瞬态诱发性耳声发射和畸变产物耳声发射筛查的新生儿55例（110耳）进行226、6781、000 Hz探测音鼓室声导抗测试,对比分析各种探测音鼓室声导抗的图形,声导纳值、声纳值和声导值,并进行统计学分析。结果：226 Hz探测音鼓室声导纳图、声纳图和声导图以双峰型为主,分别占90.0%、99.1%和85.5%,少数为单峰型,无多峰型出现;678 Hz探测音鼓室声导纳图、声纳图和声导图以单峰型为主,分别占62.7%、77.3%和62.7%,双峰型分别占34.6%、20.9%和31.8%,少数出现三峰型;1 000 Hz探测音鼓室声导纳图、声纳图和声导图以单峰型为主,分别占96.4%、99.1%和97.3%,极少数为双峰型,无三峰型出现。226 Hz与678 Hz探测音测试,鼓室声导纳值与声纳值、声纳值与声导值的均差异有统计学意义（均P〈0.05）;声导纳值与声导值差异无统计学意义（P〉0.05）。1 000 Hz探测音测试,鼓室声导纳值、声纳值与声导值的两两比较均差异有统计学意义（均P〈0.05）。结论：获得正常新生儿多频探测音鼓室声导抗图的图形、声导纳值、声纳值和声导值的正常范围,结果提示,1 000 Hz探测音鼓室声导抗测试可以较好反映正常新生儿的中耳功能。     

Impedance audiometry with 3-probe frequency]

The 3-probe frequency (226, 678, 1000Hz) admittance (Y), susceptance (B) and conductance (G) tympanograms were recorded from 28 normal-hearing adults with a GSI 33 Version 2 Middle-Ear analyzer, and the 3-frequency ipsilateral acoustic-reflex thresholds were measured too. In all subjects, there were normal values of tympanometric indices, such as peak compliances, peak pressures, gradients and ear canal volumes, and of ipsilateral acoustic-reflex thresholds at a 226-Hz probe tone. From 226 to 1000Hz, Y, B and G increased in magnitude while the corresponding admittance-,susceptance- and conductance-tympanogram peak pressures (PY, PB, PG) shifted towards positive evidently. In comparison with 226 Hz, the 678-Hz static admittance (Y') and static susceptance (B') values were large but had no significant differences as compared with those of 1000 Hz. The relation among Y, B and G, among PY, PB and PG, and between Y' and B' changed as a function of probe frequency from 226 to 1000 Hz. The average reflex thresholds of 25 adults (30 ears) were 83 dB HL at 226-Hz probe frequency, 91 dB at 678 Hz, and 88 dB at 1000 Hz, using a 1000-Hz tonal activator. There were significant differences among the 3 values (all P less than 0.01). The ipsilateral acoustic reflexes from 3 adults (4 ears) were present at 226-and 678-Hz probe tones, but not at 1000 Hz.     

低频和高频探测音鼓室声导抗测试在婴儿中耳功能诊断中的作用

目的评价低频和高频探测音鼓室声导抗测试在诊断婴儿中耳功能异常中的作用。方法使用GSI Tympstar中耳分析仪，对年龄5—25周的听性脑干反应（auditory brainstem response，ABR）检查正常婴儿15例（30耳）和Ⅰ波潜伏期延长提示可能存在中耳功能异常婴儿17例（20耳），进行226、678、1000Hz探测音鼓室声导抗测试的比较。结果226Hz探测音鼓室声导纳图的静态声导纳值、图形、峰压和梯度在2组间的差异无统计学意义。678Hz探测音鼓室声导纳图、声纳图及声导图在2组中均可见无峰型、单峰型、双峰型、三峰型图形，其与ABR检查的一致率分别为70．0％、58．0％、64．0％，kappa值分别为0．324、0．234、0．118。1000Hz探测音鼓室声导纳图、声纳图及声导图在正常组中单峰型分别为28耳（93．3％）、25耳（83．3％）、26耳（86．7％），在异常组中无峰型分别为15耳（75％）、17耳（85％）、13耳（65％），其与ABR的一致率分别为90．0％、92．0％、86．0％，kappa值分别为0．783、0．831、0．690。结论1000Hz探测音鼓室声导抗测试是诊断小于25周婴儿中耳功能的较准确的检查方法，226、678Hz探测音鼓室声导抗测试则不能提供这些婴儿中耳功能的准确的信息。     

Contralateral acoustic-reflex growth function in a patient with a cerebellar tumor: a case study

The contralateral acoustic-reflex growth functions (ARGFs) for 500-Hz and 1000-Hz tonal activators were obtained pre- and postsurgery in a patient with a right cerebellar tumor. The acoustic-reflex magnitude was quantified as the change in equivalent air volume at the tympanic membrane during acoustic-reflex contraction. The presurgical ARGFs were shallow in the right ear and steep in the left ear at both activator frequencies. The postsurgical ARGFs were steep, bilaterally, reflecting a return to normal in the right ear. The implications with respect to the use of the ARGF measure in differential diagnosis are discussed.     

Factors influencing the acoustic-immittance characteristics of the acoustic reflex

Measurements of the aural acoustic-immittance (admittance and impedance) characteristics of the middle-ear transmission system in humans during the quiescent (static) and reflexive states were made (N = 36) utilizing a signal-averaging technique. Three pure tones (750, 1000, and 2000 Hz) and broadband noise stimuli elicited the acoustic reflex in 2-dB steps at sound-pressure levels from 84-116 dB (tones) and 66-116 dB (noise) during ascending- and descending-intensity level runs. The contralateral middle-ear activity was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an admittance meter. A computer corrected for the ear-canal volume utilizing measurements made at ear-canal pressures of 0 and --350 daPa and then converted the conductance and susceptance values into admittance and impedance units. The results were reported in absolute and relative immittance units, including components, as a function of both stimulus sound-pressure level and intensity level above the acoustic-reflex threshold. The static immittance of the middle ear changed nonlinearly over time to lower admittance or higher impedance values. The influence of this static-immittance shift on the reflex magnitude was discussed. The largest mean reflex magnitude and the slowest rate of growth were observed with broadband noise, although eight of the 36 subjects demonstrated the largest reflex magnitude in response to one or more of the tonal stimuli. Although static-immittance values and acoustic-reflex thresholds were poorly correlated, the reflex magnitudes were proportional to static immittance. The variability of the reflex measures was similar to the variability of the static-immittance values. Finally, bi-directional changes in resistance during the reflexive state were observed and discussed.     

年龄因素对不同频率探测音声导值和声纳值测试结果的影响

目的：探讨年龄对声导纳测试的声导值和声纳值的影响。方法：采用GSI－33version2中耳分析仪，对9－72岁共9个耳科正常人按年龄分六组，均采用三种频率探测音进行声导值和声纳值检测，结果：使用226Hz探测音时，第Ⅳ组的声纳分别与第Ⅰ、Ⅱ组的比较，其差异有显著性（P＜0．05），第Ⅱ组的声导值与第Ⅵ组的比较差异有显著性（P＜0．05）；使用678Hz探测音时，第Ⅳ组的声纳值分别与第Ⅰ、Ⅱ、Ⅲ、Ⅴ组等各组的声纳值比较差异有显著性（P＜0．05），第Ⅳ组声纳值分别与第Ⅰ、Ⅱ、Ⅴ组等各组的比较差异有显著性（P＜0．05），第Ⅳ组的声导值分别为第Ⅰ、Ⅲ、Ⅴ、Ⅳ组等各组的比较差异有显著性（P＜0．05），结论：随着年龄的变化，鼓膜－中耳传音系统的质量因素作用的增长较为明显，摩擦及粘度因素作用则视声波的频率而异。     

Choice of probe tone and classification of trace patterns in tympanometry undertaken in early infancy

Tympanometry using 226 Hz, 678 Hz, and 1000 Hz probe tones was undertaken on two groups of babies, age 2 to 21 weeks. A group of 104 babies with normal ABR thresholds or TEOAEs were compared with a second group of 107 babies who had evidence of temporary conductive hearing loss based on the findings of a test battery, which included air and bone conduction ABR. The tympanograms were classified by Method 1, a simple visual classification system, and Method 2, adapted from a system described by Marchant et al (1986). The majority of tympanograms recorded in both groups using the 226 Hz probe tone were 'normal' Type A, with no significant difference in middle ear pressure or static admittance. However, both classification methods demonstrated significant differences between the two groups using the higher frequency probe tones, with Method 2 being the preferred system of classification. Tympanometry using 226 Hz is invalid below 21 weeks and 1000 Hz is the frequency of choice.     

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。     

Registrierung der druckabhängigen Komponenten der komplexen Trommelfelladmittanz beim akustischen Reflex

Summary The reflex-related change in admittance (susceptance and conductance) was measured at different static pressures in the ear canal and recorded as reflextympanogram at 220 Hz and 660 Hz probe-tone frequency.The reflex-related change of the dynamic properties was simulated in a mathematical model of the middle-ear.Susceptance, measured at 660 Hz, indicates pathological stiffness of the middle-ear system.     

Tympanometry with 226 and 1000 Hertz tone probes in infants

This study aimed at describing and analyzing tympanometric results obtained with 226Hz and 1000Hz probe tones; checking for correlations between tympanometry, otoacoustic emissions and otoscopic examination; describing abnormal results found in the evaluation procedures.MethodsDouble-blind and prospective study. Our sample included 70 babies, between 7 days and one month and 13 days of age, without risk indicators for hearing loss, evaluated in the State Neonatal Hearing Screening Program. Transient evoked otoacoustic emissions, otoscopic examination and tympanometry with 226Hz and 1000Hz probe tones were used as assessment tools. The study was approved by the Ethics Committee from the institution.ResultsStatistically significant differences were observed (p<0.05) in the tympanometric measures correlation and also between transient evoked otoacoustic emissions and compliance obtained with both probe tones. Most test results were within the normal range (94.28%). Three children (4.28%) were referred to diagnostic follow-up and one (1.42%) had middle ear dysfunction confirmed by otoscopy and 1000Hz tympanometry.Conclusions1000Hz tympanometry is the most reliable probe tone used to evaluate children under three months of age. More studies focusing on middle ear acoustics and mechanics are necessary to provide reliable and precise interpretation in the evaluation of middle ear functions in babies.     

短声作为刺激声同侧声发射阈测定之临床价值

OBJECTIVE: To define that click can substitute for pure tone as a stimulus to measure ipsilateral acoustic reflex thresholds, and to find out the effect of probe frequency on acoustic reflex thresholds. METHOD: Using middle ear analyzer (GSI 33, version 2), we measured 23 normal voluntary participants (46 ears) for getting the pure-tone generated ipsilateral acoustic reflex thresholds at different probe frequency and the click evoked ipsilateral acoustic reflex thresholds at click rate 100/s and 180/s for every ear. RESULT: For pure tone, the ipsilateral acoustic reflex thresholds at 500 Hz, 1000 Hz, 2000 Hz, were (84.35 +/- 6.96) dB, (84.65 +/- 5.93) dB, (87.96 +/- 6.36) dB by using 226 Hz probe; (93.13 +/- 6.54) dB, (92.70 +/- 6.33) dB, (93.35 +/- 5.99) dB by using 678 Hz probe; (86.52 +/- 4.72) dB, (87.48 +/- 5.00) dB, (88.30 +/- 6.16) dB by using 1000 Hz probe. For click, the ipsilateral acoustic reflex thresholds at click rate 100/s and 180/s were (89.78 +/- 6.83) dB, (92.07 +/- 7.42) dB by using 226 Hz probe; (90.44 +/- 6.76) dB, (90.65 +/- 6.38) dB by using 678 Hz probe; (88.04 +/- 6.87) dB, (88.69 +/- 7.42) dB by using 1000 Hz probe. The acoustic reflex thresholds for 678 Hz probe were higher than those obtained with 226 Hz and 1000 Hz probes. CONCLUSION: There were no artifact appearance while stimulus had been click at low rate, so click can be used for the measurement of ipsilateral acoustic reflex thresholds.     

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.     

Outer and middle ear status and distortion product otoacoustic emissions in children with sickle cell disease

The purpose of this study was to investigate distortion product otoacoustic emissions (DPOAEs) and outer/middle ear status in 12 African American children with normal hearing and homozygous sickle cell disease (SCD) and age-, gender-, and ear-matched African American controls. C. R. Downs, A. Stuart, & D. Holbert (2000) reported that DPOAE amplitudes were significantly larger for children with SCD. Because the integrity of the middle ear system directly influences OAE characteristics, it was felt that concurrent investigation of DPOAE amplitudes and outer/middle ear function in children with SCD was warranted. DPOAEs were evoked by 13 primary-tone pairs with f2 frequencies ranging from 1000 to 4500 Hz. Outer/middle ear status was assessed with tympanometry through indices of peak compensated static acoustic admittance, tympanometric width, tympanometric peak pressure, ear canal volume, and middle ear resonance frequency. Tympanograms were recorded with probe-tone frequencies of 226 and 678 Hz. DPOAE amplitudes were significantly larger for children with SCD (p < .05). There were no group differences in any of the middle ear indices (p > .05). These findings suggest that increased DPOAE amplitudes for children with SCD cannot be attributed to differences in outer/middle ear function as assessed with tympanometry.     

Can maximum comfortable loudness levels in hearing impaired listeners be predicted from ipsilateral acoustic reflex thresholds recorded with high frequency probes?

This study was designed to test the effectiveness of the ipsilateral acoustic reflex thresholds measured with low and high frequency probes in predicting the maximum comfortable loudness levels (MaxCLs) in hearing-impaired subjects using recently available sophisticated procedures for acoustic reflex and loudness measures. Loudness growth functions were measured in hearing-impaired subjects at .5, 1 and 2 kHz using a computerized procedure. The maximum level among those sound pressure levels judged as 'comfortable' was designated as the MaxCL. Acoustic reflex thresholds were measured for .5, 1 and 2 kHz activator signals using 226, 678 and 1000 Hz probes. Regression analyses suggested that acoustic reflex thresholds recorded with the 678 and 1000 Hz probes could provide an objective estimate of the MaxCLs for 1 and 2 kHz. Thus, acoustic reflex thresholds may be useful in fitting hearing aids for those subjects in whom reliable measures of MaxCLs cannot be obtained.     

Otoadmittance in normal subjects

Otoadmittance audiometry was performed on a group of young subjects (18-30 years old) with normal hearing. Mean values and standard deviations for static admittance, conductance and susceptance were computed on the basis of the point of maximum compliance, as well as the point of zero cross (drum-free position). In addition, the values of curve width for conductance and susceptance, middle ear pressure and the threshold of the acoustic reflex for pure tones and interrupted tones were evaluated. Subjects presenting an abnormality of the tympanic membrance were studied as a separate group. The results obtained in this study were compared with those reported in the literature.     

Normative multifrequency tympanometry in infants and toddlers

Multifrequency tympanometry data were measured multiple times between the ages of four weeks and two years from 33 infants/toddlers. Tympanograms were also measured from 33 adult participants. Tympanograms recorded with five probe-tone frequencies (226, 400, 630, 800, and 1000 Hz) were classified using the Vanhuyse et al model classification system (Vanhuyse et al, 1975). Admittance at +200 daPa (Y200) and middle ear admittance (Y(ME)) were calculated. The proportion of Vanhuyse et al patterns in infants and toddlers was different than in adults, especially for younger ages. Y(ME) and Y200 both increased with age. Y(ME) and Y200 data for all infant/toddler groups were significantly lower than adult values at all of the tested probe-tone frequencies. These data can be used as a guide in the clinic to assess normal tympanometric values for infants and toddlers.     

Classification of trace patterns of 226- and 1000-Hz tympanometry in healthy neonates

Objective

Accurate evaluation of middle ear function is a challenge especially in babies referred from newborn hearing screening programs. The aim was to assess the feasibility of tympanometry using 226- and 1000-Hz probe tones in neonates.

Methods

Hearing was evaluated by transient evoked otoacoustic emission (TEOAE) in 96 ears of healthy neonates in well-baby nursery. Babies with risk factors for hearing loss as identified in Joint Committee on Infant Hearing (JCIH, 1994) were excluded. Tympanograms recorded with 226 and 1000 Hz probe tones were analyzed and classified.

Results

Tympanograms were classified according to Method A (Jerger/Liden) and visual classification systems, Method B (adapted from Marchant et al.) and Method C (adapted from Kei et al.), without difficulty. In 72 ears with normal TEOAE, 226 Hz tympanograms were classified as normal in 72 ears in Methods A and B, and 16 ears in Method C. 1000 Hz tympanograms were normal in 68 ears in Method A, 72 ears in Method B and 68 ears in Method C. In 24 ears with abnormal TEOAE, 226 Hz tympanograms were interpreted as normal in most ears (23 ears in Method A, 24 ears in Method B), whereas 1000 Hz tympanograms were abnormal in 13 ears in Method A and 6 ears in Method B, possibly reflecting middle ear dysfunction.

Conclusion

In healthy neonates without risk factors for hearing loss, 1000 Hz tympanograms can be recorded and interpreted. A single-peaked tympanograms was most common in ears with normal TEOAE. In ears with abnormal TEOAE, tympanograms were classified as abnormal more frequently using 1000 Hz than 226 Hz. Implementation of tympanometry using 1000 Hz probe tone in newborn hearing screening programs may provide valuable information regarding middle ear dysfunction that may cause transient conductive hearing loss.     

不同月龄婴儿声反射与畸变产物耳声发射测试结果分析

目的探讨不同月龄婴儿226 Hz和1000 Hz探测音的中耳声反射测试与畸变产物耳声发射（DPOAE）联合筛查的意义。方法测试对象为来泸州医学院附属医院进行听力筛查或复查的188例（350耳）3天～12月龄的婴儿,分为3天～1月龄组（125耳）,2～3月龄组（89耳）,4～6月龄组（76耳）,7～12月龄组（60耳）,分别进行226、1000Hz探测音声导抗,畸变产物耳声发射测试,对226、1000Hz探测音中耳声反射引出率和DPOAE的通过率进行比较分析。结果3天～1月龄组226、1000Hz探测音声反射引出率和DPOAE的通过率分别为81％、69％、73％;2～3月龄组分别为91％、72％、74％;4～6月龄组分别为90％、83％、79％;7～12月龄组分别为43％、66％、60％。226Hz声反射引出率与DPOAE通过率差异有统计学意义（P〈0．01）,1000Hz声反射引出率与DPOAE通过率差异无统计学意义（P〉0．05）,并且DPOAE筛查结果与1000Hz探测音的声反射结果较一致。结论1000Hz探测音声导抗测试对婴儿中耳功能的诊断价值比226Hz探测音的敏感性更高,与DPOAE协同用于婴儿听力筛查具有良好的临床价值。     

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.