The effect of high-pass filtering on TEOAE in 2-month-old infants.

The aim of the present study was to investigate the effect of high-pass filtering on TEOAE obtained from 2-month-old infants as a function of filter cut-off frequency, activity states and pass/fail status of infants. Two experiments were performed. In Experiment 1, 100 2-month-old infants (200 ears) in five activity states (asleep, awake but peaceful, sucking a pacifier, feeding, restless) were tested by use of TEOAE technology. Five different filter conditions were applied to the TEOAE responses post hoc. The filter conditions were set at 781 Hz (default setting), 1.0, 1.2, 1.4 and 1.6 kHz. Results from this experiment showed that TEOAE parameters such as whole-wave reproducibility (WR) and signal-to-noise ratio (SNR) at 0.8 kHz and 1.6 kHz, changed as a function of the cut-off frequency. The findings suggest that the 1.6 kHz and 1.2 kHz filter conditions are optimal for WR and SNR pass/fail criteria, respectively. Although all infant recordings appeared to benefit from the filtering, infants in the noisy states seemed to benefit the most. In Experiment 2, the high-pass filtering technique was applied to 23 infants (35 ears) who apparently failed the TEOAE tests on initial screening but were subsequently awarded a pass status based on the results from a follow-up auditory brainstem response (ABR) assessment. The findings showed a significant decrease in noise contamination of the TEOAE with a corresponding significant increase in WR. With high-pass filtering at 1.6 kHz, 21/35 ears could be reclassified into the pass category.

Paediatric hearing screening in the community: a comparison of outcomes from transient evoked and distortion product otoacoustic emission measures.

The present study aimed to compare TEOAE screening outcomes based on different pass/fail criteria and the outcomes from TEOAE and DPOAE measures in children. For the purpose of the study, the subjects were divided into two age groups: group 1 (n = 36; mean age 2.7 months, SD 1.2), and group 2 (n = 29; mean age 37.5 months, SD 16.3). Results indicated that the agreement of screening outcomes between pass/fail criteria for the TEOAE measure and between TEOAE and DPOAE measures was significantly lower for the younger group than for the older group. The greater variability in the younger age group could be partly attributed to the higher physiological noise produced by young infants. Irrespective of the pass/fail criteria used, the findings of the present study suggest that the OAE outcomes for children with weak OAEs or OAEs obscured by excessive noise were most variable.

Transient evoked otoacoustic emissions in two-month-old infants: a normative study.

Researchers have recently reported the effects of age, sex, ear asymmetry, and subject's activity status on transient evoked otoacoustic emissions (TEOAEs). The present study aimed to expand upon such reports by describing the characteristics of TEOAE spectra obtained from a cohort of 607 two-month-old infants in community child health clinics. Results indicated significant sex, ear and activity state effects on the signal:noise ratio, response, whole wave and band reproducibility values. These findings suggest the need for TEOAE normative data to be expressed as a function of sex, ear, and activity state of infants. These characteristics of TEOAE spectra may shape future investigations into appropriate pass fail criteria for two-month-old infants.

Infant hearing screening: a comparison of two techniques.

Hearing screening programs for Australian children are known to have poor coverage in many areas. In addition, only a minority of children are screened for hearing loss before 2 years of age. However, early detection of hearing loss and early treatment are generally considered very important to successful rehabilitation outcomes. Traditional methods of screening infants have limitations with their accuracy in detecting children with hearing loss. This study compared the results obtained with a traditional questionnaire approach to screening and a newer objective technique involving otoacoustic emission measures. Poor correlation was found between pass rates for the two techniques, suggesting that the questionnaire approach is not an accurate screening method for detecting infant hearing loss. With further development, otoacoustic emission testing holds promise as an objective alternative hearing screening procedure.

Feasibility of community-based hearing screening using transient evoked otoacoustic emissions.

This study investigated the feasibility of obtaining transient evoked otoacoustic emissions for hearing screening purposes from infants and children at seven child health clinics. Factors affecting the outcomes of the community hearing screening program were examined. The subject group comprised 2305 children aged two weeks to 11 y 11 mon. Many children were attending the clinics for initial immunisation at two months of age. While there were no exclusion criteria for the 1305 young infants tested who were in this category, all other children were screened only upon receipt of a referral from clinic nurses. Results indicated that 182 children (7.9%) did not complete the screening for both ears within the time constraint (usually 15 min) of a child health clinic visit. Three hundred and sixty-two children (15.7%) failed the first screening. Of the 226 children who returned for a second screening test, separated from the first by at least two weeks, 121 children failed. With parents' consent, 107 children (4.6% of all participants) were referred for diagnostic or medical assessment. Subsequently, 77 out of 94 children who received audiological or medical assessment were found to have some degree of hearing impairment. The majority of positive screening results were associated with middle ear disorder. The results suggest that TEOAE screening has potential as a technique in the community health setting but improvements in instrumentation are required to reduce 'could not test' cases and to separate probable conductive hearing loss from cases likely to have other disorders.

Transient evoked otoacoustic emissions in infants: effects of gender, ear asymmetry and activity status.

This study examined the effects of gender, ear asymmetry and activity status of infants on various measures of transient evoked otoacoustic emission (TEOAE), including signal-to-noise ratio (SNR) and reproducibility of emissions, using TEOAE as a mass screening procedure in a community health setting. Five hundred and sixty-eight infants were screened for hearing at two months of age, before immunization. The ILO88 Otodynamic Analyzer Quickscreen program was used for all testing with pass/fail criteria similar to those used in the Rhode Island hearing assessment project. The results indicated a significant difference in SNR across sex, with females showing a higher mean SNR. The right ear was found to have higher values in 'reproducibility' and 'response level' than the left ear. A significant difference in SNR across activity states was also evident. Implications from these findings, as applied to community-based screening programs, are discussed.

[Results of health research on the drinking water supply in relation to extreme conditions]. / Ergebnisse der hygienischen Forschung zur Trinkwasserversorgung unter extremen Bedingungen.

Proceeding from historical informations on refinering of drinking water under extreme conditions the results of the development of hygiene research for minimal need of drinking water by man, for water filtration in mobile constructions and for disinfection of drinking water at situations of damages and catastrophes are given in a survey.