Transient evoked TEOAE tests allow to otoacoustic emissions non-invasively check the integrity of the cochlea. In the neonatal period, registration of OAEs can be accomplished during natural sleep. They are less time consuming and elaborate than auditory brainstem responses ABR and they are more sensitive than behavioral tests. TEOAEs are constant over long periods of time and they are reduced or absent due to various adverse influences in the inner ear. These latter characteristics may allow monitoring of the inner ear function over time e.
Rosanowski and colleagues divided tinnitus patients into those with hearing loss and those without, and they found no consistent TEOAE results between the two groups. With conflicting results, it is not prudent to conclude that OAEs give objective evidence of tinnitus; more research in this area is needed.
Perhaps the most promising area for the use of OAEs with patients with tinnitus is in the area of tinnitus monitoring. Recording OAEs before, during, and after tinnitus retraining therapy may show objective improvements in addition to subjective reports. Although not an official name, this graph is used by many to plot absolute DPOAE amplitude to obtain information regarding audiometric thresholds. It was derived from a study by Gorga and colleagues , which reported, " Certain factors must be considered when utilizing this tool: the equipment being used it is best to use the same equipment as that used in the study , acquisition factors such as L1, L2 , and the recording environment data was collected in "typical clinical conditions" Gorga et al.
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Overall, this tool is of great use clinically. An example of an adapted Gorgagram is shown in Figure 1. Figure 1. OAEs and hearing aid fittings. The concept behind this lies in the ability of OAEs to identify regions of the cochlea with damage, which can assist in programming a hearing aid. When OAEs are absent, we assume hearing loss of greater than about 25 dB HL at the frequency where the emission is absent.
In difficult to test patients, or any patient for which we cannot obtain audiometric threshold data, the absence of an OAE gives us some idea of hearing levels.
In conjunction with ABR, we can use this data to program amplification for these patients. Absent OAEs in conjunction with audiometric thresholds of 70 dB HL or greater can be an indicator of a cochlear dead region, which in turn can influence the hearing aid selection and programming.
Active Processes and Otoacoustic Emissions in Hearing
OAEs as acoustic fingerprints. Although OAEs in the cochlea may all be alike, each person's unique middle ear system and external ear change the characteristics of the OAE. Thus, an individual's OAE may be used as an "acoustic fingerprint" to unlock that person's phone or iPod! OAEs and intraoperative monitoring. Although not a new concept, using OAEs in the operating room is probably not a common practice in many places. They can also be used to assess hearing in the operating room following grommet tube insertion; however, their absence in these situations may be due to reasons not related to cochlear function such as edema, blood, mucosa, etc.
When using OAEs for any reason in the operating room, keep in mind that room noise and electrical artifact could interfere with collection. OAEs in musicians. Much like the use of OAEs in ototoxicity monitoring, OAEs can be used to provide objective confirmation of cochlear dysfunction in patients with normal audiograms. Similarities between the hearing losses in musicians and industrial workers confirm that excessive exposure to music can affect the ear as much as industrial noise exposure Hall, OAE findings can be associated with cochlear frequency specificity; therefore, difficulty hearing can be confirmed with OAEs, even in the presence of a normal audiogram.
For music professionals, maintenance of hearing not only improves quality of life, but it can preserve their employment and livelihood. Conclusion A thorough understanding of OAEs and their anatomical and physiological origin is critical for clinical decision-making. Although OAEs continue to play an important role in routine audiological assessments, they have many applications that are less commonly known.
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In addition, they hold promise for use in several areas never conceived of 10 years ago. It is exciting to think of what may be ahead for the use of OAEs. References American Academy of Audiology Position statement and clinical practice guidelines: Ototoxicity monitoring. Available from www. Outer hair cell electromotility and otoacoustic emissions.
Ceranic, B. Audiol Neurootol , 3 5 , Deltenre, P.
Auditory neuropathy with preserved cochlear microphonic and secondary loss of otoacoustic emissions. Audiology, 38 4 , Gorga, M. From laboratory to clinic: A large scale study of distortion product otoacoustic emissions in ears with normal hearing and ears with hearing loss. Hall, J. Handbook of otoacoustic emissions. LePage, E. A model for cochlear origin of subjective tinnitus: Excitatory drift in the operating point of inner hair cells.
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Hearing Research, , Rosanowski, F. Chronic tinnitus in children and adolescents.
HNO, 45 11 , Shehata, W. Acta Oto-laryngologica, 3 , Shera, C. Mechanisms of mammalian otoacoustic emission and their implications for the clinical utility of otoacoustic emissions.
Ear and hearing; 25 2 : Shiomi, Y. Hearing Research , Stach, B. Comprehensive dictionary of audiology illustrated 2nd Ed. New York: Thomson Delmar Learning. Starr, A. Cochlear receptor microphonic and summating potentials, otoacoustic emissions, and auditory pathway auditory brain stem potentials activity in auditory neuropathy. Stavroulaki, P. Otoacoustic emissions for monitoring aminoglycoside-induced ototoxicity in children with cystic fibrosis.
Active Processes and Otoacoustic Emissions in Hearing : Geoffrey A. Manley :
Arch Otolaryngol Head Neck Surg, , Swabey, M. Using otoacoustic emissions as a biometric. Classification of patients with Meniere's disease using otoacoustic emissions. Assistant Professor in the Department of Audiology at A. She has practiced privately and at several Children's Hospitals, as well as a Center for Developmental Delays, where she served as Audiology Director.
Cunningham has designed, taught, and presented courses, as well as published, on the topics of assessment and management of children with hearing loss. Cunningham, PhD. Rebekah F. Recorded Webinar. The Indiana EHDI Alert Response System EARS was created to improve follow up on babies who do not pass their newborn hearing screening, who do not receive a newborn hearing screening, or who are at risk for delayed onset hearing loss.