A cross-over, double-blind comparison of the NAL-NL1 and the DSL v4.1 prescriptions for children with mild to moderately severe hearing loss

Abstract

Abstract

The relative effectiveness of the NAL-NL1 and the DSL4.1 prescriptions for 48 children with mild to moderately severe hearing loss was studied using a double-blind, four-period, two-treatment cross-over design in Australia and in Canada. Evaluations included speech perception tests, loudness ratings, reports from parents and teachers on functional performance in real life, children's self-reports, paired-comparison judgements of intelligibility, and children's preferences in real-world environments. Electroacoustic measures of hearing aids revealed that gain differences dominated the comparison. Across trials and measures, individual Australian children consistently preferred either the NAL-NL1 or the DSL v.4.1 prescription. An overall figure of merit (FOM), calculated by averaging the standardized difference scores between prescriptions for all measures, revealed that the strongest prescription-related differences were found in Australia. On average, an advantage and preference for the NAL-NL1 prescription was associated with lesser degrees of hearing loss. This research provides evidence on the effectiveness of the NAL-NL1 and DSL v.4.1 prescriptions, and highlights the need for evaluating and fine-tuning amplification to meet the diverse needs of individual children in real life.

Sumario

Se estudió la relativa efectividad de las prescripciones NAL-NL1 y DSL 4.1 en 48 niños con pérdidas auditivas de leves a moderadamente severas, usando un estudio doble ciego, en cuatro períodos y con un diseño cruzado de dos tratamientos en Australia y en Canadá. Las evaluaciones incluyeron pruebas de percepción de la palabra, tasas de reclutamiento, auto-reportes de los niños, juicios de inteligibilidad comparados por pares y preferencias de los niños en ambientes de mundo real. Las mediciones electroacústicas de los auxiliares auditivos revelaron que las diferencias en ganancia dominaron la comparación. En todas las pruebas y mediciones, los niños Australianos individualmente prefirieron de manera consistente tanto la prescripción NAL-NL1 como la DSL v.4.1. Una figura global de mérito (FOM), calculada al promediar las puntuaciones de diferencias estandarizadas entre prescripciones de todas las medidas, revelaron que las diferencias más fuertemente relacionadas con la prescripción, se encontraron en Australia. En promedio, la ventaja y preferencias hacia la prescripción NAL-NL1 se asoció con grados menores de pérdida auditiva. Esta investigación proporciona evidencia de la efectividad de las prescripciones NAL-NL1 y DSL v.4.1 y pone de relieve la necesidad de evaluar y de afinar la amplificación para alcanzar las diversas necesi-dades individuales de los niños en la vida real.

Key Words:

• hearing aid prescription
• children
• NAL-NL1
• DSL v.4.1
• cross-over comparison
• double-blind study
• amplification

Acknowledgments

Support for this collaborative research was provided by the Oticon Foundation. We gratefully thank all the children, their families and their teachers for participation in this study.

Note

1. The participants ranged in age from 6.6 to 19.8 years. The terms ‘children’ or ‘child’ are used in this and other manuscripts in this issue to describe the samples, in accordance with the National Institutes of Health policy of defining ‘children’ as ‘individuals under the age of 21 years’.

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