Normative wideband reflectance measures in healthy neonates

The effects of cochlear implantation on middle ear function: A prospective study

OBJECTIVES

Although sound conduction mechanisms may influence by cochlear implantation (CI), it is not very clear whether, how, and to what extent these mechanisms may be influenced the pediatric population. Wideband tympanometry (WBT) is a sensitive tool to evaluate alternations in the middle ear mechanics in a wide frequency range. The current study aimed to explore CI's impacts on sound conduction across the middle ear cavity using WBT in pediatrics.

METHODS

In a prospective design, 35 unilaterally implanted children (<24 months of age) with normal temporal bone anatomy were included in this study. Traditional tympanometry (226-Hz) and WBT measures were compared for each child in the implanted and non-implanted ears preoperatively and three months postoperatively.

RESULTS

No significant changes in the "static acoustic admittance" and "peak pressure" parameters were observed between the pre-CI and post-CI conditions in the implanted and non-implanted ears in the 226-Hz tympanometry test. Wideband absorbance recordings before CI surgery exhibited a double-peaked pattern over a frequency range of 250 to 8000 Hz. The pre- and postoperative acoustic energy absorbance comparisons indicated a significantly reduced mid-frequency (1260 to 3175 Hz) and high-frequency (5040 to 8000 Hz) absorbance in the implanted ears. However, our results indicated no significant differences in sound absorbance between the pre- and postoperative conditions in non-implanted ears.

CONCLUSION

Our findings suggested that WBT is a more sensitive method than traditional tympanometry for monitoring the mechanical status of the middle ear after cochlear implantation in pediatrics. Cochlear implantation in young children can significantly reduce mid- and high-frequency acoustic absorbance measured by WBT.

Wideband Tympanometry Findings in Healthy Neonates

OBJECTIVES

 The objective of the present study was to describe pressurized wideband absorbance at tympanometric peak pressure (WBATPP) and 0 daPa (WBA0) in healthy Caucasian neonates.

SUBJECTS

 A total of 249 ears from 249 neonates who passed a test battery of 1,000-Hz tympanometry, distortion product otoacoustic emissions and automated auditory brainstem response were included in the study.

METHOD

 WBATPP and WBA0 were averaged in one-third octave frequencies from 0.25 to 8 kHz. Data were statistically analyzed for effects of frequency, ear, and gender.

RESULTS

 Normative WBATPP and WBA0 data obtained from healthy neonates are presented. There was no significant difference between WBATPP and WBA0 at all frequencies. Both WBATPP and WBA0 demonstrated a multipeaked pattern with maxima of 0.80 and 0.72 at 1.25 to 1.5 and 6 kHz, respectively, and two minima of 0.45 and 0.49 at 0.4 to 0.5 and 4 kHz, respectively. The effects of ear and gender were not significant for both WBA measures.

CONCLUSION

 Pressurized WBATPP and WBA0 data were provided for healthy Caucasian neonates. They will be useful for the assessment of middle ear function and assist in differentiating between conductive and sensorineural hearing losses in neonates.

Clinical benefit of wideband-tympanometry: a pediatric audiology clinical study

PURPOSE

Wideband-tympanometry (WBT) could give more informative data about the tympanic condition than the conventional tympanometry. In the actual literature, the clinical profit of wideband-tympanometry in pediatric audiological settings is not well evaluated. The aim of this study was to analyze the additional clinical benefit.

METHODS

150 children (281 ears) with normal hearing, at the age from 11 days up to 14;10 years, checked with pure tone audiometry or auditory brainstem responses (ABR) participated in this retrospective study. We divided in four age ranges (≤ 6 month; > 6 month ≤ 3 years; > 3 years ≤ 11 years; > 11 years). All children were evaluated with ENT examination including ear microscopy, conventional 226-Hz or 1000-Hz tympanometry and WBT. Ear canal volumes were determined.

RESULTS

Compared with literature data, our patients aged ≤ 3 years showed smaller mean ear canal volumes (≤  4 ml). We found a good statistical correlation between the WBT-results and 1000-Hz tympanometry but a rare correlation between WBT-results and ear microscopic findings. In the patients with pathologic ear microscopic results in all groups of age, a significant reduction of WBT-absorbance in 1000 Hz and 2000 Hz was found.

CONCLUSIONS

This study confirms that WBT collects additive data to detect the correct middle ear status. In pediatric audiology, WBT is an additional useful method to value middle ear problems and to analyze the character of infantile hearing loss. Standard guidelines for the interpretation of the pediatric population are needed. Hence, it will be necessary to determine these findings in a larger number of infantile ears.

Normative Wideband Acoustic Immittance Measurements in Caucasian and Aboriginal Children

Purpose The aims of this study were to develop normative data for wideband acoustic immittance (WAI) measures in Caucasian and Australian Aboriginal children and compare absorbance measured at 0 daPa (WBA₀) and tympanometric peak pressure (TPP; WBA_TPP) between the 2 groups of children. Additional WAI measures included resonance frequency, equivalent ear canal volume, TPP, admittance magnitude (YM), and phase angle (YA). Method A total of 171 ears from 171 Caucasian children and 87 ears from 87 Aboriginal children who passed a test battery consisting of 226-Hz tympanometry, transient evoked otoacoustic emissions, and pure tone audiometry were included in the study. WAI measures were obtained under pressurized conditions using wideband tympanometry. Data for WBA₀, WBA_TPP, YM, and YA were averaged in one-third octave frequencies from 0.25 to 8 kHz. Results There was no significant ear effect on all of the 7 measures for both groups of children. Similarly, there was no significant gender effect on all measures except for WBA_TPP in Aboriginal children. Aboriginal boys had significantly higher WBA_TPP than girls at 1.5 and 2 kHz. A significant effect of ethnicity was also noted for WBA_TPP at 3, 4, and 8 kHz, with Caucasian children demonstrating higher WBA_TPP than Aboriginal children. However, the effect size and observed power of the analyses were small for both effects. Conclusion This study developed normative data for 7 WAI measures, namely, WBA₀, WBA_TPP, TPP, Veq, RF, YM, and YA, for Caucasian and Aboriginal children. In view of the high similarity of the normative data between Caucasian and Aboriginal children, it was concluded that separate ethnic-specific norms are not required for diagnostic purposes.

A Longitudinal Analysis of Pressurized Wideband Absorbance Measures in Healthy Young Infants

OBJECTIVES

Wideband absorbance (WBA) is an emerging technology to evaluate the conductive pathway (outer and middle ear) in young infants. While a wealth of research has been devoted to measuring WBA at ambient pressure, few studies have investigated the use of pressurized WBA with this population. The purpose of this study was to investigate the effect of age on WBA measured under pressurized conditions in healthy infants from 0 to 6 months of age.

DESIGN

Forty-four full-term healthy neonates (17 males and 27 females) participated in a longitudinal study. The neonates were assessed at 1-month intervals from 0 to 6 months of age using high-frequency tympanometry, acoustic stapedial reflex, distortion product otoacoustic emissions, and pressurized WBA. The values of WBA at tympanometric peak pressure (TPP) and 0 daPa across the frequencies from 0.25 to 8 kHz were analyzed as a function of age.

RESULTS

A linear mixed model analysis, applied to the data, revealed significantly different WBA patterns among the age groups. In general, WBA measured at TPP and 0 daPa decreased at low frequencies (<0.4 kHz) and increased at high frequencies (2 to 5and 8 kHz) with age. Specifically, WBA measured at TPP and 0 daPa in 3- to 6-month-olds was significantly different from that of 0- to 2-month-olds at low (0.25 to 0.31 kHz) and high (2 to 5 and 8 kHz) frequencies. However, there were no significant differences between WBA measured at TPP and 0 daPa for infants from 3 to 6 months of age.

CONCLUSIONS

The present study provided clear evidence of maturation of the outer and middle ear system in healthy infants from birth to 6 months. Therefore, age-specific normative data of pressurized WBA are warranted.

Normative wideband absorbance measures in healthy neonates in Korea: A preliminary study

INTRODUCTION

The usefulness of wideband absorbance (WBA) in newborns is well-demonstrated. However, it is still not clear whether there might be a difference according to ethnicity with respect to ambient WBA; therefore, further investigation is necessary to evaluate ethnic-specific normative WBA values in newborns.

METHODS

Twenty-one newborns (41 ears) were recruited from the well-baby nursery at a tertiary referral center. All newborn infants who were born at 38 weeks' to 41 weeks' gestation with a normal birth weight (range: 2.5-4.5 kg) and who passed a newborn hearing screening test with distortion product otoacoustic emissions were enrolled. Ambient absorbance values were measured on frequencies ranging from 226 Hz to 6300 Hz (i.e., 250 Hz, 315 Hz, 400 Hz, 500 Hz, 620 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, and 6300 Hz). The results of median absorbance were compared with the WBA values of Caucasian infants and Korean adults.

RESULTS

The gestational age of the study group was 38 weeks ± 6.67 days. In a gender comparison, absorbance of female neonate was significantly higher at 3150 Hz, 4000 Hz, and 5000 Hz than in male. Based on the test frequencies, the medians of the Korean infant WBA values and Caucasian infants are significantly different from one another, except at 1600 Hz, 3150 Hz, and 4000 Hz. The results of a median absorbance comparison between Korean infant and adults WBA values showed that the medians of the two studies were significantly different except at 1250 Hz.

CONCLUSION

We analyzed the normative WBA values measured at ambient pressures in Korean newborns. The comparative analysis between the normative values of two different ethnic groups may infer a possible difference in the normative WBA values. The absorbance from Korean infant ears is substantially different from that from adult's ears. A large-scale study is required to establish normative WBA values to be used for the screening of outer and middle ear status in newborns.

The Effect of Ethnicity on Wideband Absorbance of Neonates with Healthy Middle Ear Functions in Malaysia: A Preliminary Study

BACKGROUND AND OBJECTIVES

Although ethnicity effect on wideband absorbance (WBA) findings was evident for adults, its effect on neonates has not been established yet. This study aimed to investigate the influence of ethnicity on WBA measured at 0 daPa from neonates with healthy middle ear functions.

SUBJECTS AND METHODS

Participants were 99 normal, healthy, full-term newborn babies with chronological age between 11 and 128 hours of age (mean=46.73, standard deviation=26.36). A cross-sectional study design was used to measure WBA at 16 one-third octave frequency points from 99 neonates comprising of three ethnic groups: Malays (n=58), Chinese (n=13) and Indians (n=28). A total of 165 ears (83.3%) that passed a battery of tests involving distortion product otoacoustic emissions, 1 kHz tympanometry and acoustic stapedial reflex were further tested using WBA. Moreover, body size measurements were recorded from each participant.

RESULTS

The Malays and Indians neonates showed almost identical WBA response across the frequency range while the Chinese babies showed lower absorbance values between 1.25 kHz and 5 kHz. However, the differences observed in WBA between the three ethnic groups were not statistically significant (p=0.23). Additionally, there were no statistically significant difference in birth weight, height and head circumference among the three ethnic groups.

CONCLUSIONS

This study showed that Malays, Chinese and Indians neonates were not significantly different in their WBA responses. In conclusion, to apply for the ethnic-specific norms is not warranted when testing neonates from population constitute of these three ethnicities.

Pressurized Wideband Absorbance Findings in Healthy Neonates: A Preliminary Study

PURPOSE

The present study aimed to establish normative data for wideband absorbance (WBA) measured at tympanometric peak pressure (TPP) and 0 daPa and to assess the test-retest reliability of both measurements in healthy neonates.

METHOD

Participants of this cross-sectional study included 99 full-term neonates (165 ears) with mean chronological age of 46.7 hrs (SD = 26.3 hrs). Of the 99 neonates, 58 were Malay, 28 were Indian, and 13 were Chinese. The neonates who passed high-frequency (1 kHz) tympanometry, acoustic stapedial reflex, and distortion product otoacoustic emission screening tests were assessed using a pressurized WBA test (wideband tympanometry). To reduce the number of measurement points, the WBA responses were averaged to 16 one-third octave frequency bands from 0.25 to 8 kHz. A mixed-model analysis of variance was applied to the data to investigate the effects of frequency, ear, gender, and ethnicity on WBA. The analysis of variance was also used to compare between WBA measured at TPP and 0 daPa. An interclass correlation coefficient test was applied at each of the 16 frequency bands to measure the test-retest reliability of WBA at TPP and 0 daPa.

RESULTS

Both WBA measurements at TPP and 0 daPa exhibited a multipeaked pattern with 2 maxima at 1.25-1.6 kHz and 6.3 kHz and 2 minima at 0.5 and 4 kHz. The mean WBA measured at TPP was significantly higher than that measured at 0 daPa at 0.25, 0.4, 0.5, 1.25, and 1.6 kHz only. A normative data set was developed for absorbance at TPP and at 0 daPa. There was no significant effect of ethnicity, gender, and ear on both measurements of WBA. The test-retest reliability of WBA at TPP and 0 daPa was high with the interclass correlation coefficient ranging from 0.77 to 0.97 across the frequencies.

CONCLUSIONS

Normative data of WBA measured at TPP and 0 daPa for neonates were provided in the present study. Although WBA at TPP was slightly higher than the WBA measured at 0 daPa at some frequencies below 2 kHz, the WBA patterns of the 2 measurements were nearly identical. Moreover, the test-retest reliability of both WBA measurements was high.

Wideband acoustic immittance for assessing middle ear functioning for preterm neonates in the neonatal intensive care unit

BACKGROUND

The primary aim of newborn hearing screening is to detect permanent hearing loss. Because otoacoustic emissions (OAEs) and automated auditory brainstem response (AABR) are sensitive to hearing loss, they are often used as screening tools. On the other hand, false-positive results are most often because of transient outer- and middle ear conditions. Wideband acoustic immittance (WAI), which includes physical measures known as reflectance and absorbance, has shown potential for accurate assessment of middle ear function in young infants.

OBJECTIVE

The main objective of this study was to determine the feasibility of WAI as a diagnostic tool for assessing middle ear functioning in preterm neonates in the neonatal intensive care unit (NICU) designed for premature and ill neonates. A further objective was to indicate the difference between the reflectance values of tones and click stimuli.

METHOD

Fifty-six at-risk neonates (30 male and 26 female), with a mean age at testing of 35.6 weeks (range: 32-37 weeks) and a standard deviation of 1.6 from three private hospitals, who passed both the distortion product otoacoustic emission (DPOAE) and AABR tests, were evaluated prior to discharge from the NICU. Neonates who presented with abnormal DPOAE and AABR results were excluded from the study. WAI was measured by using chirp and tone stimuli. In addition to reflectance, the reflectance area index (RAI) values were calculated.

RESULTS

Both tone and chirp stimuli indicated high-power reflectance values below a frequency of 1.5 kHz. Median reflectance reached a minimum of 0.67 at 1 kHz - 2 kHz but increased to 0.7 below 1 kHz and 0.72 above 2 kHz for the tone stimuli. For chirp stimuli, the median reflectance reached a minimum of 0.51 at 1 kHz - 2 kHz but increased to 0.68 below 1 kHz and decreased to 0.5 above 2 kHz. A comparison between the present study and previous studies on WAI indicated a substantial variability across all frequency ranges.

CONCLUSION

These WAI measurements conducted on at-risk preterm NICU neonates (mean age at testing: 35.6 weeks, range: 32-37 weeks) identified WAI patterns not previously reported in the literature. High reflective values were obtained across all frequency ranges. The age of the neonates when tested might have influenced the results. The neonates included in the present study were very young preterm neonates compared to the ages of neonates in previous studies. WAI measured in at-risk preterm neonates in the NICU was variable with environmental and internal noise influences. Transient conditions affecting the sound-conduction pathway might have influenced the results. Additional research is required to investigate WAI testing in ears with and without middle ear dysfunction. The findings of the current study imply that in preterm neonates it was not possible to determine the feasibility of WAI as a diagnostic tool to differentiate between ears with and without middle ear pathology.

Normative Study of Wideband Acoustic Immittance Measures in Newborn Infants

OBJECTIVE

The purpose of this study was to describe normative aspects of wideband acoustic immittance (WAI) measures obtained from healthy White neonates.

METHOD

In this cross-sectional study, wideband absorbance (WBA), admittance magnitude, and admittance phase were measured under ambient pressure condition in 326 ears from 203 neonates (M age = 45.9 hr) who passed a battery of tests, including automated auditory brainstem response, high-frequency tympanometry, and distortion product otoacoustic emissions.

RESULTS

Normative WBA data were in agreement with most previous studies. Normative data for both WBA and admittance magnitude revealed double-peaked patterns with the 1st peak at 1.25-2 kHz and the 2nd peak at 5-8 kHz, while normative admittance phase data showed 2 peaks at 0.8 and 4 kHz. There were no significant differences between ears or gender for the 3 WAI measures. Standard deviations for all 3 measures were highest at frequencies above 4 kHz.

CONCLUSIONS

The 3 WAI measures between 1 kHz and 4 kHz may provide the most stable response of the outer and middle ear. WAI measures at frequencies above 4 kHz were more variable. The normative data established in the present study may serve as a reference for evaluating outer and middle ear function in neonates.

Acoustic absorbance measurements in neonates exposed to smoking during pregnancy

OBJECTIVE

To analyze acoustic absorbance using wideband tympanometry in neonates exposed to passive smoking during pregnancy.

METHOD

A study comprising 54 neonates in the control group (CG - unexposed) and 19 in the study group (SG - exposed) was carried out. Subjects were submitted to the wideband tympanometry test and subsequent analysis of absorbance of 17 frequencies.

RESULT

Low frequencies had a lower level of absorbance compared to high frequencies for both ambient and peak pressures, with no difference between the groups.

CONCLUSION

No effect of passive smoking on acoustic absorbance measurements in neonates was observed.

Sweep frequency impedance measures in young infants: developmental characteristics from birth to 6 months

OBJECTIVE

International Journal of Audiology To study the developmental characteristics of sweep frequency impedance (SFI) measures in healthy infants from birth to 6 months.

DESIGN

All infants were assessed using high-frequency tympanometry (HFT), distortion product otoacoustic emission (DPOAE) and SFI tests. SFI measures consisted of measurement of resonance frequency (RF) and mobility (ΔSPL) of the outer and middle ear. A mixed model analysis of variance was applied to the SFI data to examine the effect of age on RF and ΔSPL.

STUDY SAMPLE

Study included 117 ears from 83 infants of different age groups from birth to 6 months.

RESULTS

The mean RF of the outer ear increased from 279 Hz at birth to 545 Hz at 4 months, whereas mean ΔSPL of the outer ear decreased from 7.9 dB at birth to 3.7 dB at 4 months of age. In contrast, the mean RF and ΔSPL of the middle ear did not change significantly with age up to 6 months.

CONCLUSIONS

Developmental characteristics should be considered when evaluating the function of the outer and middle ear of young infants (≤6 months) using the SFI. The preliminary normative SFI data established in this study may be used to assist with the evaluation.

Wideband reflectance measurements in newborns: Relationship to otoscopic findings

OBJECTIVES

Newborn hearing screening includes testing with otoacoustic emissions and the auditory brainstem response. Unfortunately, both tests are affected by the presence of material in the ear canal and middle ear such as vernix, meconium, and amniotic fluid. The objective of this study was to determine to what extent occlusion of the ear canal as seen on otoscopy affects wideband energy reflectance measurements in newborns. A secondary objective was to obtain additional normative wideband reflectance data in newborns.

METHODS

Newborns from a well-baby nursery were enrolled. Wideband energy reflectance measurements and otoscopy were done immediately after the hearing screening. Occlusion of the ear canal as seen on otoscopy was described on a scale of 0-100%.

RESULTS

A total of 156 babies were enrolled (mean age = 25 hours). A statistically significant difference in the reflectance at ambient pressure was found between the 0-70% and 80-100% occlusion groups. There was no significant difference in reflectance between the right and the left ears. The median reflectance pattern generally followed that of previous studies but in certain frequency regions the present reflectance values were higher.

CONCLUSION

A significant increase in reflectance occurs when 70%-80% of the ear-canal diameter is occluded. Taking otoscopy findings into account may improve the interpretation of reflectance measurements. However, further studies are required to better establish the relationship between canal occlusion and reflectance.

Effects of ear canal static pressure on the dynamic behaviour of outer and middle ear in newborns

OBJECTIVE

The present study investigated the effect of ear canal pressure on the dynamic behaviour of the outer and middle ear in newborns with and without a conductive condition using the sweep frequency impedance (SFI) technology.

METHODS

A test battery consisting of automated auditory brainstem response (AABR), transient evoked otoacoustic emission (TEOAE) and 1000-Hz tympanometry (HFT) was performed on 122 ears of 86 healthy newborns and 10 ears of 10 newborns with a conductive condition (failed TEOAE and HFT). The dynamic behaviour of the outer and middle ear, when the pressure applied to the ear canal was varied from 200 to -200daPa, was evaluated in terms of the sound pressure level (SPL) in the ear canal, resonance frequency (RF) and displacement (ΔSPL).

RESULTS

Application of either a positive or negative static pressure to the ear canal of healthy newborns increased the resonance frequency of the outer (RF1) and middle ear (RF2), but decreased the displacements of the outer (ΔSPL1) and middle ear (ΔSPL2). Positive static pressures resulted in lower SPL while negative static pressures resulted in higher SPL than that at ambient pressure (0daPa). At -200daPa, more than 90% of ears showed signs of collapsed ear canal. The dynamic behaviour under various positive and negative static pressures for newborn ears with a conductive condition indicated similar pattern of SPL, RF1 and ΔSPL1 responses for the outer ear as per healthy ears, but abnormal responses for the middle ear.

CONCLUSIONS

While both positive and negative pressures applied to the ear canal have the same effect of stiffening the outer and middle ear, negative pressure of up to -200daPa resulted in more than 90% of ears with a collapsed ear canal. The results of the present study do not only offer useful clinical information for differentiating healthy ears from ears with a conductive condition, but also provide information on the maturation aspects of the outer and middle ear in newborns.

Sweep frequency impedance measures in Australian Aboriginal and Caucasian neonates

OBJECTIVE

Despite high prevalence of otitis media in Aboriginal children, the acoustic-mechanical properties of their outer and middle ear during the neonatal period remain obscured. The objective of this study was to compare the acoustic-mechanical properties of outer and middle ear using Sweep Frequency Impedance (SFI) measures between Australian Aboriginal and Caucasian neonates.

METHODS

SFI data from 40 ears of 24 Aboriginal neonates (16 males, 8 females) with mean gestational age of 39.57 weeks (SD = 1.25) and 160 ears of 119 Caucasian neonates (57 males, 62 females) with mean gestational age of 39.28 weeks (SD = 1.25) serving as controls were analysed. SFI data in terms of resonance frequency (RF) and mobility of the outer and middle ear (ΔSPL) were collected from neonates who passed a test battery that included automated auditory brainstem response, distortion product otoacoustic emissions test and 1000-Hz tympanometry. SFI data were analysed using descriptive statistics and analysis of variance.

RESULTS

There was no significant difference in mean gestational age, age of testing and birth weight between the Aboriginal and Caucasian neonates. The mean resonance frequencies for the outer ear (mean RF1 = 264.9 Hz, SD = 58.6 Hz) and middle ear (mean RF2 = 1144 Hz, SD = 228.8 Hz) for Aboriginal neonates were significantly lower than that of Caucasian neonates (mean RF1 = 295.3 Hz, SD = 78.4 Hz and mean RF2 = 1241.8 Hz, SD = 216.6 Hz). However, no significant difference in the mobility of outer ear (ΔSPL1) and middle ear (ΔSPL2) between the two groups was found. Middle ear resonance was absent in 22.5% (9 ears) of Aboriginal ears but present in all Caucasian ears.

CONCLUSIONS

This study provided evidence that despite passing the test battery, Aboriginal neonates had significantly lower resonance frequencies of the outer and middle ear than Caucasian neonates. Furthermore, 22.5% of Aboriginal neonates showed no middle ear resonance, indicating the possibility of subtle middle ear issues not detected by the test battery. Reasons for the different acoustic-mechanical properties between the two ethnic groups remain unclear and require further investigation.