Towards improving the start of life of hearing impaired children

baby ear

The Background

Current advances in neonatal hearing screening techniques allow the early detection of hearing impediments in new-born babies, so that remedial actions can be taken at the earliest possible opportunity.

In subjects not affected by profound deafness, the prescription of a Behind The Ear (BTE) hearing aid is a cost-effective practice that enables many children to develop adequate speech and language skills.

A current challenge in the fitting of hearing aids is the verification of the hearing aid sound amplification performance as fitted, due to resonances in the ear canal. This verification, which is performed in adult patients through the Real Ear Measurement (REM) procedure, is not used in paediatric audiology practice, leading to uncertainties of up to 20 dB in specific frequency bands. This affects the effectiveness of the hearing aid in the critical phase of life when speech and language skills are developed.

ASDEC steps in

ASDEC has teamed up with the Clinical Audiology and the Department of Technology, De Montfort University, to explore an alternative way of verifying the fitting of hearing aids, through contactless Laser Doppler Vibrometry (LDV).

The key idea is that by measuring the vibrational response of the tympanic membrane using a LDV, the effectiveness of the hearing aid over its working frequency range can be determined. Since LDV is a stand-off measurement technique, there is no requirement for inserting a microphone probe inside the ear canal, making this technique intrinsically safe for use on children and young patients.

Find out more at the 22nd International Congress on Sound and Vibration

The outcome from preliminary tests on tympanic-membrane-like models will be presented by Dr Aldo Rona at the 22nd International Congress on Sound and Vibration, Florence, 12-16 July 2015.

These tests have explored the repeatability of the LDV based procedure and its sensitivity to targeting, tympanic membrane shape and thickness.

The results are promising in terms of the sensitivity of the measurements to the aiming of the LDV and show that, as long as measurements are performed in the neighbourhood of the membrane geometric centre, a variability of 1.5 dB is obtained, which is a significant improvement over the current uncertainty of up to 20 dB. The effects of membrane shape and thickness are more significant, indicating that patient-specific calibrations of the new technique is required.

These preliminary results have confirmed that LDV can in principles used to improve the fitting of hearing aids to children, so that they more easily develop the communication and language skills that enable them to enjoy life as fully integrated members of society.

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