Equivalent Hearing Loss in Children – comparison of Cochlear Implant and Hearing Aid
Sandra Nekes, Frans Coninx, Anneke Vermeulen
Aim
Early intervention is the key to spoken language for hearing impaired children. A severe hearing loss diagnosis in a young child raises the urgent question on the type of optimal hearing aid device. But indication criteria differ not only from country to country, but sometimes from clinic to clinic.
As there is no recent data on comparing selection criteria for a specific hearing aid device, the goal of the Hearing Evaluation of Auditory Rehabilitation Devices (hEARd) project (Coninx & Vermeulen, 2012) evolved to collect and analyze interlingually comparable normative data on the speech perception performances of children with hearing aids and children with cochlear implants (CI). The hEARd project followed the Equivalent Hearing Loss concept of the 1990s (Snik et al., 1997a). The performance of CI users is interpreted in comparison to the performance of hearing aid users in relation to their degree of hearing loss. Collected data allows to derive an equivalent hearing loss (EHL) value. It can give an indication, from which level of hearing loss on a CI can offer statistically better speech perception in the used tests and up to which level a child benefits adequately from hearing aids compared to the average performance of children using hearing aids.
Method
In various institutions for hearing rehabilitation in Belgium, Germany and the Netherlands the Adaptive Auditory Speech Test AAST (Coninx, 2005) – amongst other tests of the BELLS software (Battery for the evaluation of listening and language skills) – was used in the hEARd project, to determine speech perception abilities in kindergarten and school aged children, using CI or hearing aids with a hearing loss acquired within their first year of life.
Achieved results in audiometric procedures such as speech perception in quiet or in noise as well as the performance when using high frequency speech material were matched to the unaided hearing loss values of children using hearing aids and compared to results of children using CI.
277 data sets of hearing impaired children were analyzed. Results of children using hearing aids were summarized in groups as to their unaided hearing loss values. The grouping was related to the World Health Organization’s (WHO) grading of hearing impairment from mild (25–40 dB HL) to moderate (41–60 dB HL), severe (61 80 dB HL) and profound hearing impairment (80 dB HL and higher). These groups’ performances were compared to the performances of children using CI.
Results
AAST
speech recognition results in quiet showed a significantly better
performance for the CI group in comparison to the group of profoundly
impaired hearing aid users as well as the group of severely impaired
hearing aid users. The same trend could be observed in the
performance of high frequency speech material. However the CI users’
performances in speech perception in noise did not vary from the
hearing aid users’ performances who have a profound or severe
hearing loss.
Within the collected data analyses showed that
children with a CI show an equivalent performance on speech
perception in quiet as children using hearing aids with a “moderate”
hearing impairment. The CI users’ performance on speech perception
in noise appeared poorly compared to their overall performance.
Conclusion
The
test battery turned out to be a useful diagnostic tool to evaluate
the performance on auditory speech perception skills in hearing
impaired children. It allows a comparison of performances based on
different parameters such as type of technical hearing aid
device.
For the daily educational routine it can be concluded
that especially children using hearing aids with hearing losses
greater than 60 dB have distinctly greater difficulties in the
auditory perception of speech compared to children with lower hearing
losses or children using CI. Speech perception in an educational
environment needs to be ensured. Educational concepts as well as the
optimization of technical devices should be topics in the ongoing
consultation of child and family.
This is one task that needs
to be addressed by the field of educational audiology as well as a
necessary reevaluation of outcomes with upcoming developments of
technical hearing devices.