Static Acoustic Admittance Research Articles

Achados timpanométricos em neonatos com emissões otoacústicas presentes: medidas e interpretações

Timpanometria avalia condições funcionais da orelha média. Quando realizada em neonatos abaixo de quatro meses de idade pode gerar dúvidas. Sondas de alta freqüência têm sido investigadas na busca por resultados mais confiáveis. OBJETIVO: Descrever e analisar interpretações de características e medidas obtidas na timpanometria em neonatos com freqüências de 226, 678 e 1000Hz. MATERIAL E MÉTODO: Os 110 neonatos avaliados tinham idade entre 6 e 30 dias, não apresentaram fatores de risco e tinham emissões otoacústicas presentes. A timpanometria foi realizada com o analisador GSI-33-II, na Divisão de Educação e Reabilitação dos Distúrbios da Comunicação, São Paulo, em 2004. FORMA DE ESTUDO: Clínico prospectivo. RESULTADOS: Observou-se equilíbrio nas curvas pico único e pico duplo em 226Hz, maior ocorrência de assimétrica em 678Hz e de pico único em 1000 Hz. Houve significância de gênero na medida volume equivalente do meato acústico externo, em 226Hz, e na medida admitância acústica estática de pico compensado, em 1000Hz. O protocolo inglês apresentou quase 100% de normalidade em 678 e 1000Hz. CONCLUSÃO: A sonda de 1000Hz apresentou melhores resultados na caracterização da normalidade. O protocolo inglês mostrou-se eficiente em diminuir variabilidades das medidas. Os resultados podem ser usados como guia no diagnóstico da timpanometria.

Tympanometry in neonates with normal otoacoustic emissions: measurements and interpretation

SummaryTympanometry is used in evaluating middle ear functional conditions. Before six months of age its results may be misleading. High frequency studies aim to provide more valid procedures. Aim: To describe and discuss tympanometric measurements and the interpretation in normal hearing neonates at 226, 678 and 1000Hz. Method: 110 neonates that were analyzed had normal otoacoustic emissions and no risk for hearing impairment. The age range was 6 to 30 days. Curves were obtained using the GSI-33-II, at the “Divisão de Educação e Reabilitação dos Distúrbios da Comunicação”, São Paulo, in 2004. Study design: Clinical prospective. Results: There was a balance between single and double peak curves at 226Hz. Most of the curves were asymmetric at 678Hz, and single-peaked at 1000Hz. quantitative measurements showed a significant gender difference in the Equivalent Ear Canal Volume at 226Hz and on the Peak Compensated Static Acoustic Admittance at 1000Hz. The English protocol showed that almost 100% of ears were normal at 678 and 1000Hz. Conclusion: 1000Hz yielded superior results for characterizing normality. The English protocol was efficient to reduce the variability of tympanometric measurements. Data from this study may be used as a guide for diagnosis using tympanometry in neonates.

Stapedial Reflex and Ears With High Static Acoustic Admittance

To evaluate modified acoustic reflex diagnostic protocols for a group of individuals (n = 9) with high peak compensated static acoustic admittance (Y(tm)) tympanograms. A modified procedure designed to improve acoustic stapedius reflex threshold (ASRT) measurements in individuals with high-admittance tympanograms was employed in both an experimental and a control group. ASRTs were measured at 0.5, 1.0, and 2.0 kHz, ipsilateral and contralateral. Measurements were obtained within each condition for 7 ear canal pressures that were set to 0, +/-50, +/-100, and +/-150 daPa (relative to tympanometric peak pressure [TPP]). Though measuring ASRTs at -50 daPa (relative to TPP) in the high-admittance and normal groups did not result in significantly better thresholds than at TPP, the absent reflex rate was reduced when the ear canal pressure was changed by -50 daPa during ASRT measurements. Based on this sample, it is suggested that a patient presenting with high peak compensated static acoustic admittance (peak Y(tm) > or = 2.1 mmho) undergo ASRT evaluation with the ear canal pressure set to -50 daPa (relative to TPP).

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

ObjectiveTo assess the utility of low- and high-frequency tympanometry in the diagnosis of middle ear dysfunction in Chinese infants. MethodsTympanograms 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 with prolonged wave I latencies (17 infants, 20 ears), suggesting middle ear dysfunction, using a GSI Tympstar middle ear analyzer Version II. ResultsThe 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. Conclusion1000 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.

Tympanometric and Acoustic Stapedius Reflex Measures in Older Adults: The Blue Mountains Hearing Study

Tympanometric peak pressure, peak compensated static acoustic admittance (peak Ytm) and acoustic stapedius reflex (ASR) thresholds were obtained for a representative sample of 1565 older Australians who were participants in the Blue Mountains Hearing Study (BMHS). No significant age or gender effects were found for tympanometric peak pressure. Peak Ytm measures, however, decreased with age in the left ear only across all age groups and were consistently higher for men than for women. After allowing for hearing loss, the effect of age on ASR thresholds was inconsistent. An increase in ASR thresholds with age was observed at selected frequencies but only when measured contralaterally, and these changes were not clinically significant. Overall, our findings suggest that current normative data for peak Ytm is too restricted for application in the older population, but there is insufficient evidence to warrant alternative normative data for the ASR threshold range in this same population.

Tympanometric norms for Chinese schoolchildren

Current tympanometric norms have acknowledged the relevance of age as an influencing factor. However, little attention has been afforded to other potentialities such as the non-pathological effects of gender, ear asymmetry, and racial heritage. This study aimed to examine normative tympanometric findings in a large sample of Chinese schoolchildren. Using a Madsen 901 Middle Ear Analyzer, data was collected from 269 children (538 ears), ranging in age from 6.2–12.7 years (mean = 9.4 years, SD = 1.7), in Jiangsu province. Descriptive statistics were calculated for the parameters of equivalent ear canal volume (χ = 1.03, SD = 0.25, 90% = 0.68–1.46), peak compensated static acoustic admittance (χ = 0.58, SD = 0.34, 90% = 0.26–1.13), tympanometric width (χ = 112, SD = 36, 90% = 62–156), and peak pressure (χ = − 25, SD = 30, 90% = − 85 + 10). Statistically significant ear asymmetry and grade/age effects were established, although differences found were minor. In comparison with past studies in Caucasian paediatric populations, the Chinese normative data displayed minimal disparities.SumarioSe ha reconocido en las normas timpanométricas actuales la relevancia de la edad como un factor de influencia. Sin embargo, se ha puesto poca atención a otros factores potenciales como el efecto no patológico del género, la asimetría entre oídos y la herencia racial. Este estudio intenta examinar los hallazgos normativos timpanométricos en una gran muestra de escolares Chinos. Se utilizó un analizador de oído medio Madsen 901 y se colectaron datos de 269 niños (328 oídos) con edades entre 6.2 y 12.7 años (media = 9.4 años, DS = 1.7) en la provincia de Jiangsu. Se calcularon estadísticas descriptivas para los parámetros de equivalencia del volumen del conducto auditivo externo (χ = 1.03, SD = 0.25, 90% = 0.68–1.46), la admitancia acústica estática pico compensada (χ = 0.58, SD = 0.34, 90% = 0.26–1.13), la amplitud del timpanograma (χ = 112, SD = 36, 90% = 62–156), y la presión pico (χ = − 25, SD = 30, 90% = − 85 + 10). Se establecieron los efectos estadisticamente significativos en cuanto a asimetría de oídos y diferencia grado/edad, aunque las diferencias encontradas fueron menores. Los datos normativos mostraron disparidades mínimas, en comparación con otros estudios en la población pediátrica China.

Diagnostic value of tympanometry using subject-specific normative values

Tympanometry has proven valuable in the diagnosis of otitis media in infants. The classification used in the Finnish otitis media studies has resulted in high specificity yet only moderate sensitivity. We aimed to explore the benefit of using each subject's individual previous test results (obtained at previous visits of the children when diagnosed healthy) as normative values. Specific aim was to assess this approach in increasing sensitivity in the diagnosis of otitis media. We used tympanometric (GrasonStadler GSI 38) results of children in the Finnish otitis media vaccine trial obtained at pre-scheduled 7-month visits (if ears found healthy) and at the first subsequent sick visit with respiratory infections and potential otitis media within a 90-day period after the 7-month visit. Children with recent otitis media within the previous month and tympanometric tests with documented interfering factors were excluded. Pneumatic otoscopy was used as the reference method for the diagnosis of otitis media. Altogether 2476 children at the 7-month visits were examined; after exclusions data on 1759 children were available for analysis. Of these children, 630 were brought to at least one sick visit defined above. Finally, data on 906 ears were available for analysis. Entirely flat type B tympanograms predicted otitis media accurately; also high-peaked tympanograms were accurate in predicting normal middle ear status. For the moderate-peaked curves in-between, absolute and relative changes in the tympanometric variables from the 7-month visit to the sick visit were explored for accurate prediction of otitis media; decrease in curve height by at least 2/3 was found most valuable. Sensitivity of the type B tympanogram was 61% and specificity 99% at the sick visit. The sensitivity increased to 67% with a specificity of 98%, if results with the ratio of static acoustic admittance (height of the curve) at the sick visit compared to the previous healthy visit <0.35 were also considered abnormal together with type B curve in indicating otitis media. The subject-specific normative values were not found especially useful, although a slight increase in sensitivity was achieved without compromizing specificity.

Energy transmittance predicts conductive hearing loss in older children and adults.

The test performance of a wideband acoustic transfer function (ATF) test and 226-Hz tympanometry was assessed in predicting the presence of conductive hearing loss, based on an air-bone gap of 20 dB or more. Two ATF tests were designed using an improved calibration method over a frequency range (0.25-8 kHz): an ambient-pressure test and a tympanometric test using an excess static pressure in the ear canal. Wideband responses were objectively classified using moment analyses of energy transmittance, which was a more appropriate test variable than energy reflectance. Subjects included adults and children of age 10 years and up, with 42 normal-functioning ears and 18 ears with a conductive hearing loss. Predictors were based on the magnitudes of the moment deviations from the 10th to 90th percentiles of the normal group. Comparing tests at a fixed specificity of 0.90, the sensitivities were 0.28 for peak-compensated static acoustic admittance at 226 Hz, 0.72 for ambient-pressure ATF, and 0.94 for pressurized ATF. Pressurized ATF was accurate at predicting conductive hearing loss with an area under the receiver operating characteristic curve of 0.95. Ambient-pressure ATF may have sufficient accuracy to use in some hearing-screening applications, whereas pressurized ATF has additional accuracy that may be appropriate for hearing-diagnostic applications.

Tympanometric norms for Chinese young adults.

To obtain tympanometric norms in Southern Chinese young adult population and compare the results with data obtained for a Caucasian population. 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. 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. The tympanometric norms obtained in this study are recommended when evaluating middle ear function among Southern Chinese young adults.

Tympanometric Screening Norms for Adults.

The purpose of this study was to reexamine the Margolis and Heller (1987) normative tympanometric data (also American Speech-Language-Hearing [ASHA], 1990 interim norms) using a strict control over subject age and gender. Normative values for peak, compensated static acoustic admittance (Peak Ytm), acoustic equivalent volume (Vea), and tympanometric width (TW) were determined for 102 young adults with normal hearing. Relative to the Margolis and Heller normative values, significant differences were found for Vea and TW. Although statistically significant, these differences were small and of little clinical importance. However, significant and clinically important gender differences in young adults were observed for each of the tympanometric measures. Compared to males, females had lower Peak Ytm values, smaller Vea values, and higher TW values.

Multiple Frequency Tympanometry

Three methods for compensating multiple frequency acoustic admittance measurements for ear canal volume were studied in 26 men with normal middle ear transmission systems. Peak compensated static acoustic admittance (magnitude of y) and phase angle (phi) were calculated from sweep frequency tympanograms (226-1243 Hz in 113 Hz increments). Of the procedures used to compensate for volume in rectangular form, the ear canal pressure used to estimate volume had the largest effect on the estimate of middle ear resonance. Median resonance was 800 Hz for admittance measurements compensated at 200 daPa versus 1100 Hz for measurements compensated at -350 daPa. The remaining two methods, compensation of susceptance only versus both susceptance and conductance and compensation using the minimum volume versus separate volumes at each frequency, did not affect estimates of middle ear resonance. Estimates of middle ear resonance from compensated phase angle measurements also were compared with estimates of resonance from admittance and phase difference curves. Although resonance could not be estimated from the phase difference curve, resonance estimated from the admittance difference curve agreed with the estimate from compensated phase angle.

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.

Validity and Reliability of Tympanometric Measures for Pediatric Patients

Sensitivity and specificity of static acoustic admittance (SAA) and tympanometric width (TW) were assessed for 116 pediatric patients. Otologic examination was the validation criterion. Reliability of immediate repeat tympanometric measures (SAA, TW, peak pressure, and estimate of ear canal volume) was also evaluated. A statistically significant change in SAA, with a larger SAA on measure two than measure one, was observed. No significant change across the two sequential measures was observed for TW, peak pressure, or the estimate of ear canal volume. The sensitivity and specificity data collected are discussed with respect to assisting clinicians in selecting tympanometric criteria suitable to their own clinical situation.

Tympanometric Measures of Eustachian Tube Function

The purpose of this study was to develop instructions and procedures and to establish a normal data base for four tympanometric tests of Eustachian tube function: Valsalva, Toynbee, Inflation, and Deflation. Data were obtained for 24 young adults (48 ears) with normal hearing and normal middle-ear function. The tympanograms were analyzed for differences between baseline and experimental (postmaneuver) and baseline and posttest tracings for seven measures: tympanogram peak pressure, peak acoustic admittance, static acoustic admittance, negative gradient, positive gradient, and negative and positive acoustic-admittance values at +/- 400 daPa. The results indicated a statistically significant difference only in peak pressure for baseline and experimental tympanograms. Peak-pressure shifts were most pronounced for the Valsalva and Toynbee procedures. The small pressure shifts characteristic of the Inflation and Deflation procedures coupled with the potential for instrumental error severely limit the use of these procedures as means of obtaining reliable indices of tubal function.

Perstimulatory adaptation of acoustic reflex in normally hearing subjects

This was an investigation of acoustic-reflex adaptation in ten adults in each age decade between 20 and 79 years. Reflex-activating stimuli, presented by earphone to the ear contralateral to the acoustic-immittance probe, were four tones (0.5, 1.0, 2.0, and 4.0 kHz) and two filtered noises. Sound pressure levels were +5, +10, +15, and +20 dB re: acoustic-reflex threshold. Stimulus duration was 60 s. Reflex responses were measured with both components of aural acoustic admittance. Custom software was written for automated digitization, storage, quantification, and plotting of the responses. Statistical analyses of conductance and susceptance data included static acoustic admittance, acoustic-reflex threshold. maximum amplitude of reflex, rate of adaptation, and shift of baseline during reflex activation. Adaptation rate was highest for the 4.0- and 2.0-kHz activators and varied with stimulus level. Comparison of multiple regressions revealed age-related trends in measures of adaptation. [Work supported by VA-RER&amp;D.]

A Report of Acoustic Admittance Parameters in Normal Ears

The acoustic measurement of middle ear function is presently accomplished with electroacoustic instruments which measure the difference in flow of acoustic energy through the middle ear as a function of variable air pressure gradient across the tympanic membrane. The result is displayed in the form of a curve called a tympanogram, which may be analyzed by its configuration, or may provide the computational basis for the determination of static acoustic impedance or its parameters. Descriptive data has previously been defined in reactive or resistive components of the acoustic impedance, or the acoustic impedance itself, depending upon the instrumentation used. The present study explores the clinical measurement of acoustic admittance, which is the reciprocal of acoustic impedance, and compares the results of this measurement on 100 normal human middle ears with the previously developed normative data. Normal ranges for the acoustic susceptance and acoustic conductance, as well as the complex acoustic admittance, are developed which will serve as ranges for the clinical study of static acoustic admittance of the middle ear. The results compare well with data previously developed with mechanical acoustic instrumentation and also provide evidence of the source of variability in certain pathological conditions.