Ipsilateral and contralateral acoustic reflexes in neonates

Ipsilateral and contralateral acoustic reflexes were studied in neonates using 220 and 660 Hz probe tones and 500, 1000, 2000, and 4000 Hz activators. Activator sound pressure level was measured in all ears. Ipsilateral and contralateral reflexes were detected three times more frequently with a 660 Hz probe tone than with a 220 Hz probe tone. The maximum detection rate (76%) occurred with 1000 and 2000 Hz ipsilateral activators and the 660 probe tone. There was no significant difference between neonatal and adult ipsilateral thresholds at 500, 1000, and 4000 Hz. Neonatal intrameatal sound pressure levels for ipsilateral activators were found to be significantly higher than would be indicated from the otoadmittance meter manufacturer's specifications.     

Wideband reflectance measures of the ipsilateral acoustic stapedius reflex threshold

OBJECTIVE: The purpose of this study was to develop a method for acoustically measuring the ipsilateral acoustic stapedius reflex threshold by using wideband shifts in energy reflectance and admittance. DESIGN: A group of 27 young adult subjects with normal hearing participated in the study. Contralateral reflex thresholds were first measured for a 4000 Hz activator tone (maximum level, 92 dB SPL), using a clinical method with a 226 Hz probe tone. Ipsilateral and contralateral reflex thresholds were then measured by using an experimental wideband reflectance and admittance system that used a band-filtered click (200 to 2000 Hz) as the probe stimulus, presented simultaneously with the 4000 Hz activator tone. Reflex thresholds for the wideband system were determined by using statistical tests of the magnitude of the reflex responses as well as their correlation with other reflex responses. RESULTS: Clinical and experimental reflex thresholds were obtained for 9 of the 27 subjects for all conditions. Clinical reflex thresholds were absent for 8 subjects for whom experimental reflex thresholds were present and were present for 5 subjects who had absent experimental reflex thresholds for one or more conditions. An additional 5 subjects had absent reflex thresholds in all conditions, consistent with the low maximum level of the activator. Wideband measures of contralateral reflex thresholds were approximately 3 dB lower than those obtained with the clinical system. The magnitudes of the group means of the reflex responses were similar for ipsilateral and contralateral stimulations. CONCLUSIONS: Wideband measures of reflectance and admittance may be used to estimate the ipsilateral acoustic stapedius reflex threshold by separating in frequency the spectral energies of the wideband probe stimulus from the activator stimulus. This technique holds promise for measuring reflex thresholds for individuals with absent reflex thresholds through the use of standard clinical methods.     

High frequency immittance for neonates: a normative study

CONCLUSION: High frequency immittance measurements demonstrate promise in clarifying middle ear status for neonates but age- and gender-specific norms should be consulted. OBJECTIVE: To describe high frequency immittance measurements using a 1000 Hz probe tone for a sample of 278 neonatal ears (0-4 weeks of age) in order to compile normative tympanometric and acoustic reflex criteria. SUBJECTS AND METHODS: Assessment of neonatal ears included 1000 Hz probe tone immittance measurements (tympanograms and ipsilateral acoustic reflexes), and distortion product oto-acoustic emission (DPOAE) screening. Results were compared and normative values were compiled for immittance measures in ears controlled for normal middle ear functioning (n=250). RESULTS: Comparison of immittance results to OAE screening outcome provides estimates of sensitivity and specificity for middle ear fluid with tympanometry of 57% and 95%, and 57% and 90% for acoustic reflex presence, and 58% and 87% for combined tympanogram and acoustic reflex results, respectively. Normative data indicate that static peak admittance values differ significantly across gender and age with the 5th percentile cut-off value for the entire sample at 1.4 mmho. The 90% range of tympanic peak pressure normative values increases with increasing age from 140 daPa for neonates 1 week of age to 210 daPa for neonates 2-4 weeks of age. Acoustic reflexes were elicited at 93+/-9 dB with a 90% normality range of 80-105 dB.     

Identification of neonatal hearing impairment: ear-canal measurements of acoustic admittance and reflectance in neonates

OBJECTIVES: 1) To describe broad bandwidth measurements of acoustic admittance (Y) and energy reflectance (R) in the ear canals of neonates. 2) To describe a means for evaluating when a YR response is valid. 3) To describe the relations between these YR measurements and age, gender, left/right ear, and selected risk factors. DESIGN: YR responses were obtained at four test sites in well babies without risk indicators, well babies with at least one risk indicator, and graduates of neonatal intensive care units. YR responses were measured using a chirp stimulus at moderate levels over a frequency range from 250 to 8000 Hz. The system was calibrated based on measurements in a set of cylindrical tubes. The probe assembly was inserted in the ear canal of the neonate, and customized software was used for data acquisition. RESULTS: YR responses were measured in over 4000 ears, and half of the responses were used in exploratory data analyses. The particular YR variables chosen for analysis were energy reflectance, equivalent volume and acoustic conductance. Based on the view that unduly large negative equivalent volumes at low frequencies were physically impossible, it was concluded that approximately 13% of the YR responses showed evidence of improper probe seal in the ear canal. To test how these outliers influenced the overall pattern of YR responses, analyses were conducted both on the full data set (N = 2081) and the data set excluding outliers (N = 1825). The YR responses averaged over frequency varied with conceptional age (conception to date of test), gender, left/right ear, and selected risk factors; in all cases, significant effects were observed more frequently in the data set excluding outliers. After excluding outliers and controlling for conceptional age effects, the dichotomous risk factors accounting for the greatest variance in the YR responses were, in rank order, cleft lip and palate, aminoglycoside therapy, low birth weight, history of ventilation, and low APGAR scores. In separate analyses, YR responses varied in the first few days after birth. An analysis showed that the use of a YR test criterion to assess the quality of probe seal may help control the false-positive rate in evoked otoacoustic emission testing. CONCLUSIONS: This is the first report of wideband YR responses in neonates. Data were acquired in a few seconds, but the responses are highly sensitive to whether the probe is fully sealed in the ear canal. A real-time acoustic test of probe fit is proposed to better address the probe seal problem. The YR responses provide information on middle-ear status that varies over the neonatal age range and that is sensitive to the presence or absence of risk factors, ear, and gender differences. Thus, a YR test may have potential for use in neonatal screening tests for hearing loss.     

The clinical utility of ipsilateral stapedius reflex tests.

Ipsilateral stapedius reflex testing has been evaluated in 166 patients. It proves of value in defining the state of an ear (1) opposite to a unilateral conductive loss; (2) the less hard-of-hearing ear in the presence of bilateral asymmetrical sensorineural hearing losses where the worse ear has sufficiently severe loss to prevent a contralateral reflex from being elicited; (3) in patients with absent contralateral acoustic reflexes at 500, 1000, and 2000 Hz; and (4) in suspected central lesions. The test is still bedevilled by artifacts which are produced in the ear rather than the machine; atypical results must be evaluated with extreme caution.     

Impedance audiometry in the squirrel monkey. Effect of middle ear surgery.

The two principal components of impedance audiometry, the tympanogram and acoustic reflexes, were measured preoperatively and postoperatively in seven squirrel monkeys subjected to experimental middle ear surgery. A probe-tone frequency of 1,200 Hz yielded both tympanograms and acoustic reflex thresholds roughly comparable to analogous data in humans at a probe-tone frequency of 220 Hz. Both tympanograms and acoustic reflex thresholds could be obtained reliably and with comparative ease. In general, postoperative data were modified in the expected fashion by the experimental middle ear surgery. Impedance audiometry appears to be a worthwhile and useful technique for monitoring middle ear status in the squirrel monkey.     

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.     

Acoustic reflex thresholds in normal and cochlear-impaired ears: effects of no-response rates on 90th percentiles in a large sample

Ninetieth percentile cutoffs for acoustic reflex thresholds (ARTs) were determined for a sample of 2,748 ears of 1,374 subjects with normal hearing and sensorineural loss of cochlear origin. All subjects had measurable hearing (less than or equal to 110 dB HL, ANSI-1969) at all three activator frequencies (500, 1000, and 2000 Hz). Cutoff values including "no responses" ("absent" reflexes at 125 dB HL) were higher than those excluding no responses when hearing losses were greater than about 55 dB. The 90th percentiles including the effects of no responses identified ears with retrocochlear involvement for hearing losses as great as about 756 dB. For greater hearing losses at the activator frequency, the no-response rate for both cochlear and retrocochlear cases is too high to enable them to be differentiated by acoustic reflex thresholds. The 90th percentiles are derived at each activator frequency collapsed across ears. It is therefore necessary to determine the probabilities that normal or cochlear-impaired ears will have one, two, or three frequencies at which the ARTs exceed their respective 90th percentiles. It was found that among normal and cochlear-impaired ears, 12.2% have one ART elevated above the 90th percentile, but only 5.6% have two or three elevated ARTs. Clinical implications are discussed.     

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.     

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.     

Assessment of the efferent auditory system in children with suspected auditory processing disorder: the Middle ear muscle reflex and contralateral inhibition of OAEs

Objective: To determine whether children aged 7 to 12?years with listening difficulties show objective evidence for efferent auditory function based on measurements of medial olivo-cochlear and middle ear muscle reflexes.

Design: Click-evoked otoacoustic emissions recorded with and without contralateral broadband noise and ipsilateral and contralateral tonal (1000, 2000?Hz) middle ear muscle reflex thresholds were examined.

Study sample: 29 children diagnosed with suspected auditory processing disorder (APD) and a control group of 34 typically developing children participated in this study.

Results: Children with suspected APD had poorer performance on auditory processing tests than the control group. Middle ear muscle reflex thresholds were significantly higher at 2000?Hz in the suspected APD group for contralateral stimulation. MOC inhibition effects did not differ between APD and control groups.

Conclusions: This research supports earlier studies showing altered acoustic reflexes in children with APD. No group differences were found for the MOC reflex measures, consistent with some earlier studies in children with APD.     

Ipsilateral acoustic reflex stimulation in normal and sensorineural impaired ears: a preliminary report.

Ipsilateral acoustic reflex thresholds were measured at 1,000 Hz and 2,000 Hz in 38 subjects with normal hearing and in 107 subjects with a symmetrical sensorineural hearing loss. Acoustic reflex thresholds were approximately six dB better for ipsilateral vs. contralateral stimuli for both subject groups. High ipsilateral reflex thresholds were associated with larger static compliance values in the sensorineural hearing impaired subjects. Reversed reflexes (increasing compliance with muscle contraction) were observed for ipsilateral stimulation in five per cent (two) of the normal hearing subjects, and 23 percent (25) of the sensorineural hearing impaired subjects. The number of reversed reflexes was greater for subjects with higher hearing thresholds and higher ipsilateral acoustic reflex thresholds. The results suggest that quantitative use of the ipsilateral acoustic reflex requires additional research. At present it seems prudent to use ipsilateral acoustic reflex measurements as a qualitative rather than a quantitative tool, e.g. in confirming the status of one middle ear when the other has a conductive hearing loss. However, even this limited role has a considerable clinical potential.     

Contralateral acoustic reflex thresholds for tonal activators using wideband energy reflectance and admittance.

The purpose of this study was to evaluate a new method for estimating the acoustic reflex threshold incorporating wideband (250-8000 Hz) measures of energy reflectance and admittance (M. P. Feeney & D. H. Keefe, 2001). The wideband technique incorporates both a correlation method to assess the pattern of the reflex-induced shifts in reflectance and admittance across frequency and a magnitude method to determine if the amplitude of the shifts exceeds baseline variability. Contralateral reflex thresholds for 1000- and 2000-Hz activators were obtained for 34 young adults with both the wideband method and a clinical method using a 226 Hz probe tone. Average reflex thresholds obtained with the new method were 12 to 13.7 dB lower than than obtained with the clinical method. When the bandwidth of analysis of admittance and reflectance responses was limited to 250 to 2000 Hz, the reduction in reflex thresholds was accompanied by the rejection of 96% of nonactivator-baseline responses as reflexes. The method holds promise for extending reflex threshold testing to patients with reflexes elevated beyond current equipment limits, for reducing the sound levels used in reflex testing, and for obtaining sensitive measures of reflex threshold in infants.     

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.     

Aural Acoustic Stapedius-Muscle Reflex Threshold Procedures to Test Human Infants and Adults

Power-based procedures are described to measure acoustic stapedius-muscle reflex threshold and supra-threshold responses in human adult and infant ears at frequencies from 0.2 to 8 kHz. The stimulus set included five clicks in which four pulsed activators were placed between each pair of clicks, with each stimulus set separated from the next by 0.79 s to allow for reflex decay. Each click response was used to detect the presence of reflex effects across frequency that were elicited by a pulsed broadband-noise or tonal activator in the ipsilateral or contralateral test ear. Acoustic reflex shifts were quantified in terms of the difference in absorbed sound power between the initial baseline click and the later four clicks in each set. Acoustic reflex shifts were measured over a 40-dB range of pulsed activators, and the acoustic reflex threshold was objectively calculated using a maximum 10 likelihood procedure. To illustrate the principles underlying these new reflex tests, reflex shifts in absorbed sound power and absorbance are presented for data acquired in an adult ear with normal hearing and in two infant ears in the initial and follow-up newborn hearing screening exams, one with normal hearing and the other with a conductive hearing loss. The use of absorbed sound power was helpful in classifying an acoustic reflex shift as present or absent. The resulting reflex tests are in use in a large study of wideband clinical diagnosis and monitoring of middle-ear and cochlear function in infant and adult ears.     

The relationship between MOC reflex and masked threshold

Otoacoustic emission (OAE) amplitude can be reduced by acoustic stimulation. This effect is produced by the medial olivocochlear (MOC) reflex. Past studies have shown that the MOC reflex is related to listening in noise and attention. In the present study, the relationship between strength of the contralateral MOC reflex and masked threshold was investigated in 19 adults. Detection thresholds were determined for 1000-Hz, 300-ms tone presented simultaneously with one repetition of a 300-ms masker in an ongoing train of masker bursts. Three masking conditions were tested: 1) broadband noise 2) a fixed-frequency 4-tone complex masker and 3) a random-frequency 4-tone complex masker. Broadband noise was expected to produce energetic masking and the tonal maskers were expected to produce informational masking in some listeners. DPOAEs were recorded at fine frequency intervals from 500 to 4000 Hz, with and without contralateral acoustic stimulation. MOC reflex strength was estimated as a reduction in baseline level and a shift in frequency of DPOAE fine-structure maxima near 1000-Hz. MOC reflex and psychophysical testing were completed in separate sessions. Individuals with poorer thresholds in broadband noise and in random-frequency maskers were found to have stronger MOC reflexes.     

正常婴儿1000Hz探测音及多频率扫描声导纳测试分析

目的分析正常婴儿1000 Hz探测音及多频率扫描声导纳检测的临床特征。方法对164例正常听力婴儿（250耳）的1000 Hz探测音声导纳图,用基线法分型并测量正峰声导纳值;通过声纳差（ΔB）-频率函数曲线和相位角差（Δθ）-频率函数曲线检测中耳共振频率。运用SPSS11.0软件,分年龄段分别统计正峰声导纳、共振频率和相位角差（Δθ）的平均值、标准差、中位数、5%分位数、95%分位数及95%置信区间。结果全部样本均可测得基线上正峰声导纳值,各年龄组的5%分位数均≥0.2 mmho;各年龄组共振频率从311.01～599.06 Hz递增,相位角差（Δθ）的绝对值平均值从44.52～22.84递减。结论高频率探测音声导纳检测和多频率扫描声导纳检测,充分反映婴儿中耳声学特性的转变过程,更适用婴儿的中耳功能评估。     

Estimating the acoustic reflex threshold from wideband measures of reflectance, admittance, and power.

OBJECTIVE: A method was developed to estimate the contralateral acoustic reflex threshold using shifts in wideband energy reflectance, admittance magnitude and power. DESIGN: In the first experiment contralateral reflex thresholds for a noise activator were estimated on three adult participants using reflectance, admittance and power measurements at frequencies from 250 to 8000 Hz. The reflex threshold was defined using a magnitude and a correlation technique, both having the property of examining the pattern of the reflex-induced shift across a fairly broad frequency range (250 to 2000 Hz). In the second experiment, the magnitude method was modified to include an F test for the comparison of the magnitude of reflex-induced shifts in reflectance, admittance and power relative to response differences in a no-activator baseline condition. Data from four additional participants then were analyzed across a broader frequency range using a method that combined magnitude and correlation methods of estimating reflex thresholds. RESULTS: Acoustic reflex thresholds were obtained using reflectance, admittance and power-level measures in all subjects in both experiments. Individual reflex threshold estimates were as much as 24 dB lower than with the clinical system, with an average of approximately 14 dB lower for the three participants in the first experiment, and approximately 18 dB lower for the four participants in the second experiment. CONCLUSIONS: Wideband measures of reflectance, admittance and power were successfully used to estimate acoustic reflex thresholds in seven participants. A reflex threshold test was devised based on the magnitude of the response shift in the presence of a contralateral activator, and the similarity of the response shift spectra across frequency between successive activator levels. Across all participants in the study, the new test yielded a more sensitive measure of the acoustic reflex threshold than the clinical method. This finding has both clinical and theoretical implications for the study of the acoustic reflex.     

Early development of the acoustic reflex

Acoustic reflex testing was conducted on 2-day-old and on 6-week-old infants to determine how frequently, if at all, the acoustic reflex occurs, if it can be reliably observed, and also to determine what is the mean normal acoustic reflex threshold for pure tones and broad-band noise in these populations. Twenty normal infants were tested in each group. Each infant was considered to be normal by the following criteria: full term, normal pregnancy normal pregnancy and delivery, birth weight greater than 2500 g, 5-min Apgar of 7 or greater, and considered to be not at risk for hearing loss by the absence of any high risk factors. Subjects were tested following feedings. Acoustic reflexes were obtained from subjects with normal tympanograms (+/- 50 mm H2O) for 500, 1,000, 2,000, and 4,000 Hz and broad-band noise stimuli. Behavioral responses were common, requiring quieting pauses in testing and repeated stimulation for habituation of the behavioral component. Acoustic reflexes were observed, and normative reflex threshold data were obtained. The number of reflexes obtained and the mean acoustic reflex thresholds for these age-groups are reported.     

Adaptation of the acoustic reflex

Acoustic reflex adaptation is reviewed in normal and abnormal auditory systems. The measurement variables affecting the acoustic reflex threshold are discussed with reference to the intensity level above reflex threshold at which the adaptation is measured. The effects of the activator frequency and activator intensity level on the time course of normal reflex adaptation are reviewed. The diagnostic application of acoustic reflex adaptation is discussed with reference to the different definitions of abnormality found in the literature. The acoustic reflex patterns, including absence, threshold, and adaptation of the reflex, are reported in patients with different degrees of hearing loss, in order to identify the false-positive rates associated with cochlear hearing losses. Finally, the diagnostic accuracy of acoustic reflexes is discussed in subjects having lesions of the CNVIII, brain stem, CNVII, and neuromuscular systems. In summary, a method is advocated for measuring acoustic reflex adaptation over 10 seconds, which allows analysis at both 5 and 10 seconds. Further research is needed on procedural variables including activator intensity level and ipsilateral recording methods, which may increase the diagnostic accuracy of acoustic reflex adaptation.