Assistive Listening Knowledge Base
  • Peer-reviewed study

Effect of a processing delay between direct and delayed sound in simulated open fit hearing aids on speech intelligibility in noise

From https://assistivelisteningknowledgebase.org/evidence/roth-2024/ · record checked 9 October 2026

  • Roth S, Müller F-U, Angermeier J, Hemmert W, Zirn S
  • Frontiers in Neuroscience 17:1257720

Independent (Offenburg University of Applied Sciences and Technical University of Munich; German Research Foundation, DFG)

Summary

Measured speech intelligibility in noise when a quieter direct sound and a louder, slightly delayed copy reach the ear together, as in an open-fit hearing aid.

Key findings

  • 13 listeners with normal hearing took part and 11 completed both sessions; hearing loss was simulated by low-pass filtering the direct sound; delays of 1.75, 3.5 and 7 ms; speech from the front and noise from the side, over headphones.
  • With the direct sound and delayed copy in one ear only, the speech reception threshold worsened significantly as the delay grew; the abstract reports a median change from -18.1 to -14.7 dB SNR.
  • With the same delay in both ears there was no significant change.
  • The direct sound did not prevent the loss. The authors attribute this to backward masking: with the delayed copy more than 20 dB louder, it dominated perception.

Limits

Normal-hearing listeners with simulated loss; short delays only; headphone simulation without room reflections.

Read the original

pmc.ncbi.nlm.nih.gov/articles/PMC10805375

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Cited in

Cite this source

Roth S, Müller F-U, Angermeier J, Hemmert W, Zirn S. Effect of a processing delay between direct and delayed sound in simulated open fit hearing aids on speech intelligibility in noise. Frontiers in Neuroscience 17:1257720. 4 January 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC10805375/ (accessed 9 October 2026).

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