A comparison of NAL and DSL prescriptive methods for paediatric hearing-aid fitting

predicted speech intelligibility and loudness

Teresa Y C Ching, Earl E. Johnson*, Sanna Hou, Harvey Dillon, Vicky Zhang, Lauren Burns, Patricia Van Buynder, Angela Wong, Christopher Flynn

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)


Objective: To examine the impact of prescription on predicted speech intelligibility and loudness for children. Design: A between-group comparison of speech intelligibility index (SII) and loudness, based on hearing aids fitted according to NAL-NL1, DSL v4.1, or DSL m[i/o] prescriptions. A within-group comparison of gains prescribed by DSL m[i/o] and NAL-NL2 for children in terms of SII and loudness. Study sample: Participants were 200 children, who were randomly assigned to first hearing-aid fitting with either NAL-NL1, DSL v4.1, or DSL m[i/o]. Audiometric data and hearing-aid data at 3 years of age were used. Results: On average, SII calculated on the basis of hearing-aid gains were higher for DSL than for NAL-NL1 at low input level, equivalent at medium input level, and higher for NAL-NL1 than DSL at high input level. Greater loudness was associated with DSL than with NAL-NL1, across a range of input levels. Comparing NAL-NL2 and DSL m[i/o] target gains revealed higher SII for the latter at low input level. SII was higher for NAL-NL2 than for DSL m[i/o] at medium- and high-input levels despite greater loudness for gains prescribed by DSL m[i/o] than by NAL-NL2. Conclusion: The choice of prescription has minimal effects on speech intelligibility predictions but marked effects on loudness predictions.

Original languageEnglish
Pages (from-to)S29-S38
Number of pages10
JournalInternational Journal of Audiology
Issue numberS2
Publication statusPublished - Dec 2013
Externally publishedYes



  • Children
  • DSL m[i/o]
  • DSL v4.1
  • Hearing-aid prescription
  • Loudness
  • NAL-NL1
  • NAL-NL2
  • SII
  • Speech intelligibility

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