Canadian Journal of Speech-Language Pathology and Audiology

Matching real-ear targets for adult hearing aid fittings: NAL-NL1 and DSL v5.0 prescriptive formulae

Author(s) Sandra Baker
Lorienne Jenstad
Volume 41
Number 2
Year 2017
Page(s) 227-235
Language English
Category Research Article
Keywords NAL-NL1
DSL v5.0
Abstract The value of using real-ear measures when fitting hearing aids has been well researched and the information is readily available in the literature. However, a review of recent research showed that there is limited evidence to determine whether real-ear targets for gain and output can be achieved with current technology. Seven experienced clinicians fitted hearing aids to real-ear targets using one of two prescriptive methods: National Acoustic Laboratories, Non-Linear, version 1 (NAL-NL1) and Desired Sensation Level, version 5 (DSL v5.0, adult targets). One hundred ears were assessed for DSL v5.0 and 134 ears were assessed for NAL-NL1 to determine how closely the fittings matched real ear targets. The results indicate that a hearing aid can be matched to target within ±5 dB regardless of the number of gain adjustment handles, the manufacturer, or the style; with the exception of severe/profound hearing loss, particularly in the high frequencies.

L’utilité des mesures in situ pour l’ajustement des appareils auditifs a fait l’objet de plusieurs recherches. L’information à ce sujet est par ailleurs facilement accessible dans la littérature. Néanmoins, une récente recension des écrits a montré qu’il y a peu de données à savoir s’il est possible d’atteindre des cibles in situ pour le gain et le niveau de sortie avec la technologie actuelle. Afin de déterminer à quel point les ajustements correspondaient aux cibles in situ, sept cliniciens ont ajusté 100 appareils auditifs avec la méthode DSL v5.0 Desired Sensation Level, version 5 (DSL v5.0, adult targets) et 134 avec la méthode National Acoustic Laboratories, Non-Linear, version 1 (NAL-NL1). Les résultats indiquent qu’un appareil auditif peut être ajusté à ±5 dB de la cible quel que soit le nombre de bandes réglables, le fabricant ou le style à l’exception des cas de pertes auditives sévères ou profondes, particulièrement pour les pertes en hautes fréquences.
Record ID 1213

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