A randomized controlled trial of nonlinear frequency compression versus conventional processing in hearing aids: Speech and language of children at three years of age

Abstract

Objective: To determine the effect of nonlinear frequency compression (NLFC) on children's development of speech and language at three years of age. Design: A randomized controlled trial was conducted as part of the population-based longitudinal study on outcomes of children with hearing impairment (LOCHI). Participants were randomly assigned to fitting with NLFC (Phonak Naida V SP or UP) or with conventional processing in hearing aids, prescribed by using either the NAL or the DSL formula. Standardized tests of speech production, receptive and expressive language were administered, and parent ratings were collected. All assessments were double-blinded. Study sample: Participants were 44 of the 450 children in the LOCHI cohort. Results: Compared to children using conventional processing, receptive and expressive language was higher but receptive vocabulary and consonant articulation scores were lower for children who use NLFC. There was increased substitution of affricates by fricatives for children using NLFC, compared to children using conventional amplification. After allowing for the effect of multiple demographic variables, the difference in global language scores between groups was not significant (effect: 0.8 [95% confidence interval: − 6.7, 8.3]). Conclusions: There is insufficient evidence to indicate a difference in language ability between children using NLFC and those using conventional amplification.

Key Words::

• Nonlinear frequency compression
• hearing aids
• children
• randomized controlled trial
• language
• speech production
• functional performance
• CDI
• DEAP
• PEACH
• PLS-4
• PPVT

Acknowledgements

We gratefully thank all the children, their families, and their teachers for participation in this study. We thank Kathryn Crowe and Nicole Mahler-Thompson for their assistance in data collection, and the many persons who served as clinicians for the study participants or assisted in other clinical or administrative capacities at Australian Hearing, Hear and Say Centre, the Royal Institute for Deaf and Blind Children, and the Shepherd Centre. The project described was partly supported by Award Number R01DC008080 from the National Institute on Deafness and other Communication Disorders. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute on Deafness and other Communication Disorders or the National Institutes of Health.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

The authors acknowledge the financial support of the HEARing CRC, established and supported under the Cooperative Research Centres Program - an Australian Government initiative. Phonak Ltd. provided the Naida V SP and UP hearing aids used in this study.