Acoustic Immittance Measures Basic And Advanced Practice Pdf Test

acoustic immittance measures basic and advanced practice pdf test

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Acoustic Immittance Measures: Basic and Advanced Practice (Core Clinical Concepts in Audiology)

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. 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. Fifty-six at-risk neonates 30 male and 26 female , with a mean age at testing of WAI was measured by using chirp and tone stimuli.

In addition to reflectance, the reflectance area index RAI values were calculated. Both tone and chirp stimuli indicated high-power reflectance values below a frequency of 1. Median reflectance reached a minimum of 0. For chirp stimuli, the median reflectance reached a minimum of 0.

A comparison between the present study and previous studies on WAI indicated a substantial variability across all frequency ranges. 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. 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. Congenital hearing loss has been described as the most common sensory birth defect and is estimated to affect one to six in every newborns Wrightson, A known risk factor for the congenital hearing loss is a premature birth which necessitates a stay in the neonatal intensive care unit NICU Wrightson, Currently, automated auditory brainstem response AABR and otoacoustic emission OAE hearing screening methods are used to identify possible hearing loss in well-babies as well as at-risk premature neonates.

Both these screening procedures may be influenced by middle ear conditions. While tympanometry uses a single frequency stimulus, WAI measures function across a range of frequencies Hunter et al.

WAI includes measures, such as wideband reflectance and wideband absorbance. Information on middle ear status was thus shown to improve the ability to predict hearing status Hunter et al. WAI tests have also demonstrated better identification of middle ear pathology in neonates than either or 1 kHz probe tone tympanometry Hunter et al. Hearing loss in early childhood and infancy often goes undetected because it exhibits no obvious indication and symptoms.

This may lead to false-positive results. Accurate early identification of PCHL is especially problematic in the neonatal population because of the high prevalence of otitis media with effusion Hunter et al. Distinguishing middle ear conditions from sensorineural hearing loss is important to improve hearing screening programme efficacy and for appropriate referrals Boudewyns et al.

In addition, Vartiainen reported delayed diagnosis in infants with PCHL because of coexistent transient middle ear pathology. Measures of middle ear dysfunction are therefore essential for audiological diagnosis of PCHL JCIH, and should be routinely incorporated in hearing screening protocols Hunter et al.

Immittance testing by using a higher probe tone frequency 1 kHz is recommended for diagnostic testing in infants younger than 4 months because it is more sensitive to middle ear dysfunction than conventional Hz tympanometry Hunter et al.

WAI measurements of the middle ear can provide information about how well the middle ear functions across the traditional audiometric frequency range, instead of at a single frequency, as is the case with tympanometry Feeney et al. The technique uses a broad range of frequencies from 62 Hz to 13 Hz and includes a measure of power reflectance as well as admittance and impedance quantities. According to Hunter et al. Power reflectance is highest at frequencies below Hz and above Hz Hunter et al.

WAI has the potential to increase the accuracy of diagnosing middle ear pathologies in infants failing newborn hearing screening Keefe et al.

Keefe et al. This finding suggests that information on middle ear status improves the ability to correctly refer neonates for diagnostic hearing assessments and improves the ability to predict hearing status.

WAI is, therefore, recommended as an adjunct tool within newborn hearing screening programmes. The effect of anatomic differences on WAI patterns in healthy infants has been investigated by several researchers. They reported that infants have lower middle ear compliance and higher resistance compared to adults, which was attributed to ear canal wall movement at lower frequencies.

This results in a clear separation in energy reflectance values between 1-month-old infants and adults for responses of less than 0. Shahnaz et al. Hunter et al. A few days after birth, when these newborns passed DPOAE screening, reflectance values improved decreased with normalisation of middle ear function in frequency ranges involving 2 kHz and greater.

The DPOAE test is, therefore, often used as the reference standard to determine normal middle ear function in infants. However, the DPOAE alone may not accurately identify minor or sub-clinical middle ear pathologies Kemp, and hence may not serve as an ideal reference standard Hunter et al. Results showed a clear separation in reflectance between NICU neonates and adults for responses of less than 0. NICU neonates had lower reflectance values than adults at the low frequencies Shahnaz, Shahnaz reported a mean gestation age of It is unclear, however, whether this was the gestation age at birth or the gestation age at time of testing.

Newborn hearing screening routinely takes place prior to discharge from NICU, which may mean that preterm neonates undergo hearing screening at a younger age than that of the infants tested by Shahnaz The current study, therefore, aimed to determine the feasibility of using WAI for assessing middle ear functioning of preterm neonates in the NICU.

A cross-sectional exploratory design yielding quantitative data was used for the study. At-risk preterm neonates with a gestation age of 32—37 weeks mean age at testing: The study coincided with a routine hearing screening service offered at these hospitals by a private audiology practice. The carers for preterm neonates with a gestation age of 32—37 weeks who were admitted to the NICU were given the opportunity to participate in the study.

Male and female neonates were accepted as participants in the study. In total, the carers for 56 preterm neonates ears who passed both DPOAE and AABR hearing screening in one or both ears provided written informed consent for participation. WAI measurements could be obtained in 75 ears by using a chirp stimulus, in 82 ears by applying a tone-stimulus and in 59 ears by using both chirp and tone stimuli. Mean gestational age at the time of testing was Fifty infants Twenty-six neonates were female and 30 neonates were male.

WAI by using either a tone or a chirp stimulus, or both, was performed on the neonates who passed their hearing screens and for whom informed consent was obtained. This system screens both ears simultaneously at an intensity of 35 dBnHL and 37 clicks per second. Power reflectance which is part of WAI is the square of pressure reflectance and the ratio of reflected power over incident power Shahnaz et al.

RAI can be applied to both the continuous chirp stimulus reflectance function and the discrete tone-stimulus function. The RAI has the same unit percentage as reflectance Hunter et al.

The commercial HearID system model 3. Probe tubes were covered with a silicone rubber tip size ER10C 4. The same rubber tip size was used for all the neonates tested. This specific probe tip was used because of its easy and stable insertion in the ear canal.

The rubber tips were considered more appropriate in size for the neonate ear Hunter et al. Each test session for all the neonates tested consisted of two WAI measurements in each ear one for each stimulus type, namely chirp and tone stimuli.

The wideband chirp stimulus was presented at a volume of dB SPL repeatedly for an average of 1 s. The chirp stimulus data consisted of a frequency range from 0. The 9-tone series Hz, Hz, Hz, Hz, Hz, Hz, Hz, Hz and Hz was presented simultaneously at a volume of dB SPL The grouping of frequencies, which were averaged to determine the RAI, was determined by using the software for each individual measurement completed in accordance to similar reflectance values at adjacent frequencies e.

The same method was described and followed by Hunter et al. Testing was conducted in the NICU. The same audiologist conducted all the procedures. These tests were performed as the initial hearing screening stage 1 as part of a UNHS programme. The relevant protocol specifies that testing should consist of no more than two attempts by using the same screening technique on each ear JCIH, For WAI measurements at least two measurements were completed per ear, one for each channel in the probe chirp and tone stimuli.

The ear that was most accessible was tested first. In certain cases, the probe had to be refitted between measurements because of noisy conditions and inaccurate probe placement. Because NICU ambient noise levels are typically high, a major difficulty during the testing was to keep the noise levels low.

It was important to make sure that the neonate was as quiet as possible and in a restful state before testing commenced. To achieve this, neonates were tested after feeding, while in natural sleep or in an awake and quiet state. Pacifiers were used if needed to sooth the neonates as well as swaddling. The HearID system made it possible to repeat tests.

This was carried out if it was possible to settle down the neonate sufficiently. An expected challenge was to keep noise levels as low as possible while conducting the tests. In the current study, the best chirp stimulus and tone-stimulus measurements were automatically selected within a test session by using a default algorithm in the software. This algorithm is described by Hunter et al. The software that was used during the screening process did not provide warnings to the tester as to whether noise levels were unacceptable.

To remove high noise and off-target stimulus levels, therefore, the data were post hoc screened.

Acoustic Immittance Measures: Basic and Advanced Practice (Core Clinical Concepts in Audiology)

Background: The electrically evoked stapedial reflex threshold ESRT has been shown to be a good predictor of upper stimulation level for cochlear implant recipients. Previous research has shown that the ESRT may be recorded at lower stimulation levels and with a higher incidence of success with the use of higher frequency probe tones e. Research has also shown that the acoustic reflex may be recorded at lower stimulus levels with the use of wideband reflectance when compared to the acoustic reflex threshold recorded with a conventional acoustic immittance measurement. Purpose: The objective of this study was to compare the ESRT recorded with acoustic immittance and wideband reflectance measurements. Research Design: A repeated measures design was used to evaluate potential differences in ESRTs with stimulation at an apical, middle, and basal electrode contact with the use of two different techniques, acoustic immittance measurement and wideband reflectance. Study Sample: Twelve users of Cochlear Nucleus cochlear implants were included in the study.

Request 90 Day Exam Copy. Add to Cart. OAEs now play an important role in hearing screening and the clinical assessment of children and adults. The text begins with a succinct overview of OAEs and a historical description of their discovery and emergence as a clinical tool. The book is concise, but comprehensive, and covers the essentials of the subject from innovative and up-to-date perspectives. The second edition features updates across all chapters, including current research findings and changing perspectives on OAE taxonomy.

Laboratory exercises and clinical cases from actual practice are provided, with focused questions to elicit classroom discussion. This book is a volume in the Core Clinical Concepts in Audiology series. From the Foreword: "Acoustic Immittance Measures: Basic and Advanced Practice by Lisa Hunter and Navid Shahnaz is a long-overdue update on important test procedures that are applied each and every day in clinical audiology practice. The book begins with a current review of the principles underlying acoustic immittance, including anatomy and physiology of the outer and middle ear. Separate chapters are then devoted to a practical discussion of each immittance measure, including singlefrequency tympanometry, multiple-frequency tympanometry, the acoustic stapedial reflex, and wideband reflectance. Wide band reflectance is a novel approach for evaluation of middle ear function. The final two book chapters are devoted to a systematic description of specific clinical applications of acoustic immittance in infants and children with varied auditory disorders.

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Acoustic Immittance Measures In Clinical Audiology A Primer


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The primary aim of newborn hearing screening is to detect permanent hearing loss.

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Acoustic immittance tests, typically performed and supervised by audiologists, play a vital role in the detection and diagnosis of middle ear pathologies. Although.