Assistive Listening Knowledge Base
  • Peer-reviewed laboratory study

Time delay and frequency analysis of remote microphones

From https://assistivelisteningknowledgebase.org/evidence/andreatta-2025/ · record checked 13 October 2026

  • Andreatta E, Caregnato I, Selmo A, Gulli A, Onofrei MG, Orzan E
  • Audiology Research 15(5):123

Independent (authors report no external research funding; IRCCS Burlo Garofolo paid the publication charge through Ricerca Corrente RC 05/21); two authors employed by Acustica Caregnato

Summary

Measured the delay and frequency response of two proprietary 2.4 GHz remote-microphone systems used with behind-the-ear hearing aids, alone and mixed with the hearing aids' own microphones.

Key findings

  • Two remote microphones from different manufacturers, each paired with a hearing aid, were measured in a semi-anechoic test chamber.
  • Total delay through remote microphone and hearing aid was about 23-24 ms for one system and 33-35 ms for the other; the hearing aids alone added about 5-7 ms.
  • When the remote-microphone signal and the hearing aid's own microphones had similar gain, the combined response showed comb-filter ripples.
  • The authors conclude that similar transmission systems do not have the same delay, so any timing alignment has to be set per model and brand.
  • Sections 2 and 3.1 describe 5-cycle tone bursts at 750, 1500 and 3000 Hz, at 70 dB SPL, comparing a reference microphone with a measurement microphone in a 2 cc coupler. Two compression settings were used. HA1 alone took about 6-7 ms and HA2 about 5-7 ms; RM1 plus HA1 took about 23-24 ms and RM2 plus HA2 about 33-35 ms.
  • The Funding Statement distinguishes no external funding for the research from funding of the article processing charge by IRCCS Burlo Garofolo under project RC 05/21.
  • The Funding Statement distinguishes no external research funding from the publication charge paid by IRCCS Burlo Garofolo under project RC 05/21; the author affiliations identify two authors at Acustica Caregnato.

Limits

Two proprietary systems, not Auracast; idealised semi-anechoic conditions; no listener testing.

Read the original

www.mdpi.com/2039-4349/15/5/123

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Cited in

Cite this source

Andreatta E, Caregnato I, Selmo A, Gulli A, Onofrei MG, Orzan E. Time delay and frequency analysis of remote microphones. Audiology Research 15(5):123. 25 September 2025. https://www.mdpi.com/2039-4349/15/5/123 (accessed 13 October 2026).

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