Hearing-aid safety

A comparison of estimated threshold shifts for gains recommended by NAL-NL2 and DSL m[i/o] prescriptions for children

Teresa Y C Ching, Earl E. Johnson*, Mark Seeto, John H. Macrae

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Objective: To investigate the predicted threshold shift associated with the use of nonlinear hearing aids fitted to the NAL-NL2 or the DSL m[i/o] prescription for children with the same audiograms. For medium and high input levels, we asked: (1) How does predicted asymptotic threshold shifts (ATS) differ according to the choice of prescription? (2) How does predicted ATS vary with hearing level for gains prescribed by the two prescriptions? Design: A mathematical model consisting of the modified power law combined with equations for predicting temporary threshold shift (Macrae, 1994b) was used to predict ATS. Study sample: Predicted threshold shift were determined for 57 audiograms at medium and high input levels. Results: For the 57 audiograms, DSL m[i/o] gains for high input levels were associated with increased risk relative to NAL-NL2. The variation of ATS with hearing level suggests that NAL-NL2 gains became unsafe when hearing loss > 90 dB HL. The gains prescribed by DSL m[i/o] became unsafe when hearing loss > 80 dB HL at a medium input level, and > 70 dB HL at a high input level. Conclusion: There is a risk of damage to hearing for children using nonlinear amplification. Vigilant checking for threshold shift is recommended.

Original languageEnglish
Pages (from-to)S39-S45
Number of pages7
JournalInternational Journal of Audiology
Volume52
Issue numberS2
DOIs
Publication statusPublished - Dec 2013
Externally publishedYes

Keywords

  • Children
  • DSLm[i/o]
  • Hearing-aid prescription
  • Hearing-aid safety
  • NAL-NL2
  • Threshold shift

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