Ambient noise levels and infant hearing screening programs in developing countries: An observational report

Abstract

Abstract

Considering that current newborn/infant hearing screening (NHS) instruments were designed primarily for use in developed countries, this study set out to ascertain the potential effects of higher ambient noise levels on transient-evoked otoacoustic emissions (TEOAE) in sub-Saharan Africa. Data was drawn from two hospital-based and community-based NHS programs in Lagos, Nigeria, with a total screened population of 11 893 infants. Two automated TEOAE screening devices—Echo-Screen and ECHOCHECK—were available for this study. Ambient noise levels ranged from 61.0–90.5 dBA in the hospital wards and 55.6–82.5 dBA in the community health centers. One TEOAE model could not be activated at the prevailing noise levels. No significant pattern was observed in average noise levels and overall TEOAE referrals across all screening sites. However, the false-positive rates ranged from 1.4–13.8%. This study suggests that valid TEOAE screening is attainable in the Negroid race in settings with ambient noise levels up to 68 dBA but the associated high false-positive rates may necessitate additional screening with auditory brainstem response to achieve acceptable overall referral rates for timely diagnostic evaluation.

Sumario

Considerando que los instrumentos para tamiz auditivo neonatal/infantil (NHS) fueron diseñados primordialmente para su uso en países desarrollados, este estudio se propone establecer los efectos potenciales de altos niveles de ruido ambiental en las emisiones otoacústicas por productos de distorsión (TEOAE) en el Africa sub-sahariana. Los datos se obtuvieron de dos programas de NHS, con base hospitalaria y con base comunitaria de Lagos, Nigeria, con una población tamizada total de 11,893 infantes. Para este estudio estuvieron disponibles dos equipos de TEOAE – Echo-Screen y ECHOCHECK. El ruido ambiente varió de 61.0 a 90.5dBA en las salas hospitalarias y de 55.6 a 82.5 dBA en los centros de salud comunitarios. No fue posible activar un modelo de TEOAE con los niveles de ruido prevalecientes. No se observó ningún patrón de ruido promedio ni de las TEOAE que de refirieron en todos los sitios de tamiz. Sin embargo, las tasas de falsos positivos variaron de 1.4 a 13.8%. Este estudio sugiere que el tamiz con TEOAE es asequible en la raza negra en lugares con ruido ambiente de niveles hasta 68dBA pero por el nivel de falsos positivos asociado se podría requerir tamiz adicional con respuestas auditivas de tallo cerebral para alcanzar niveles aceptables de referencia para evaluación diagnóstica.

Key Words:

• Infant hearing screening
• Instrumentation
• Otoacoustic emissions
• Noise
• Developing country

Acknowledgements

The author acknowledges the kind support of Professor Linda Luxon and Professor Sheila Wirz of the Institute of Child Health, University College London, UK for the substantive UNHS pilot project that preceded this research report. The author also found the comments from two anonymous reviewers of the manuscript quite helpful.

Declaration of interest

The author has no conflict of interests to declare. Instruments for this study were provided by Natus Medical Inc, USA, Otodynamics (UK) Ltd, and the Oticon Foundation, Denmark. Hearing International Nigeria (a locally registered non-profit organization) provided financial support for all the operational costs of the project. None of the sponsors were involved in the study design, collection, analysis, and interpretation of data; the writing of the manuscript; or the decision to submit these results for publication.