Auditory speech sounds evaluation (A(section)E): a new test to assess detection, discrimination and identification in hearing impairment.

This paper describes a set of suprathreshold tests, available as a software package (A(section)E((R))), for the auditory evaluation of the hearing impaired. It uses isolated speech sounds as test material for a discrimination, identification and detection test, and is specifically suited to test preverbal children. All tests allow strict analytical interpretation. The test material and procedures are described. Their clinical use is illustrated. The authors claim that suprathreshold tests are feasible in the preverbal child, allowing analytical evaluation of the auditory capacities. These tests are complementary to the routinely used detection tests and add significantly to the hearing evaluation in preverbal children. The authors recommend the phoneme discrimination test for selection of cochlear implant candidates and for the evaluation and fitting of cochlear implants.

Normative data of the A(section)E discrimination and identification tests in preverbal children.

The A(section)E((R)) is a set of suprathreshold tests for the auditory evaluation of the hearing impaired. A particular population of interest is the hearing-impaired preverbal child. This paper reports on normative data of the A(section)E((R)) discrimination test in children aged 10 months and of the A(section)E((R)) identification tests in children aged 2 to 4 years. Normally hearing children of these ages were tested and pass criteria were defined in such a way that 95% of the hearing infants would pass the tests. With these criteria, the A(section)E((R)) discrimination test is feasible at 10 months of age and the A section signE((R)) identification test from 30 months of age.

Basic fitting and evaluation parameters of a newly designed cochlear implant electrode.

OBJECTIVE: To validate a newly designed cochlear implant electrode (TRACE) in the standard monopolar mode and compare it to a patient group implanted with a standard Nucleus Contour cochlear implant electrode. The electrode contacts of the TRACE electrode have the same active surface area for stimulation, but the position in the scala tympani is different from that of the Nucleus Contour electrode. MATERIAL AND METHODS: The following parameters, used in cochlear implant fitting and evaluation procedures, were determined: the threshold and comfort stimulation current levels; the electrode impedances; and the phoneme discrimination and speech recognition scores using the ACE speech algorithm. CONCLUSION: The new electrode does not differ significantly from the standard Nucleus Contour electrode in terms of the investigated parameters within the test group.

Cochlear implants in aplasia and hypoplasia of the cochleovestibular nerve.

OBJECTIVE: To report on the outcome of four patients with aplasia or hypoplasia of the cochleovestibular nerve who have received a cochlear implant. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: Four patients with: 1) type I aplasia; 2) type IIa aplasia; 3) type IIa hypoplasia; and 4) type IIb aplasia received a cochlear implant. All patients had corner audiograms even with hearing aids. INTERVENTION: Three patients received a LAURA multichannel implant, and one patient received a Nucleus 24 implant. MAIN OUTCOME MEASURE: Auditory performance, educational setting. RESULTS: The patients with type I and type IIb aplasia did not have auditive perception with their implant and became non-users. Both are now in a total communication educational setting. The patients with type IIa aplasia and hypoplasia had moderate audiological results with the implant with audiometrical thresholds of approximately 40-60 dB HL (pure tone average), moderate phoneme discrimination, and poor word discrimination. One child is in a total communication educational setting and the other in an oral educational setting, but the preferred mode of communication remains total communication for both. Both appear to benefit from the implant nonetheless. CONCLUSION: Patients with aplasia/hypoplasia of the cochleovestibular nerve should be counseled with caution with respect to cochlear implantation, but particular circumstances may justify the intervention. At present these circumstances seem to be a type IIa aplasia or hypoplasia in which the end organ (cochlea or common cavity) still connects to a neural structure on MRI.

A Two-stage bipodal screening model for universal neonatal hearing screening.

OBJECTIVE: A model is proposed for universal neonatal hearing screening. METHODS: The screening model is two-staged because it consists of a first test and, in case of failure (1.4% of the subjects), of a retest 3 weeks later. It is bipodal because it involves both the hospital audiologic department and a central Well Baby Organization. The idea is to have a maximal number of newborns tested at the maternity by trained audiologists and to have the Well Baby Organization trace and chase the missing subjects. The model has been evaluated during 1 calendar year (1999) in a maternity with 2,012 newborns. RESULT: The result is a coverage of 99.3%. Most newborns (97.3%) were tested at the maternity ward with a total time investment of less than 15 minutes per child. The actual test time is 2 minutes, 12 seconds (median value). The Well Baby Organization keeps track of all the results and has to test no more than 2% of the newborns. Sensitivity and specificity were not the primary outcomes of this evaluation, but they were similar to those of a previous study evaluating the screen procedure on a larger scale, giving a sensitivity of approximately 100% and a false alarm rate of 1/1,000. CONCLUSION: These figures demonstrate that universal neonatal hearing screening is feasible within the existing health care structure, with unprecedented coverage, sensitivity, and specificity.

Contralateral suppression of transient evoked otoacoustic emissions: normative data for a clinical test set-up.

HYPOTHESIS: Contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) can be used in a clinical set-up using a procedure based on a unique and robust parameter to quantify the magnitude of suppression for a subject. BACKGROUND: TEOAEs can be suppressed by delivering contralateral white noise (WN). This suppression is thought to be mediated via the efferent nerve fibers that innervate the outer hair cells. The ipsilateral TEOAE-eliciting click stimulus level and the contralateral WN level have a strong impact on the recorded level of suppression. METHODS: TEOAEs were recorded using the nonlinear stimulation mode in two conditions (with and without contralateral WN). An optimal TEOAE-eliciting click stimulus level and contralateral WN level were defined to obtain a unique and robust parameter to quantify the magnitude of suppression. RESULTS: Suppression of TEOAEs with contralateral WN can be measured in a clinical set-up using nonlinear stimulation, and the level of suppression is of the same order of magnitude as measures using the linear stimulation recording mode. The level of suppression appears to be "locked" to the interaural difference between ipsilateral TEOAE-eliciting broadband click stimulus level and the contralateral WN level. CONCLUSIONS: A procedure is proposed to record contralateral suppression in a clinical set-up, and normative data are given for a normal-hearing population (n = 60).

Neonatal hearing screening with transient evoked otoacoustic emissions--retrospective analysis on performance parameters.

The present paper reports on the implementation of a maternity based neonatal hearing-screening program in a private hospital. A retrospective analysis is performed on the test pass rate, the coverage and the number of children that become lost to follow-up. The data show a steady learning curve with a time course of several years. In the current screening practice, the test pass rate is at 99.0%, the coverage is at 96% (birth rate of 2000 per annum) and almost no babies get lost to follow-up.