Assistive Listening Knowledge Base
  • Peer-reviewed study (probe-tube measurements on one wearer)

Probe-tube measurements of ALDs: uniformity, linearity and frequency response differences

From https://assistivelisteningknowledgebase.org/evidence/salzbrenner-1991/ · record checked 13 October 2026

  • Salzbrenner LG, Newman CW, Goldstein BA
  • British Journal of Audiology 25(2):85-92

Independent (Cleveland Hearing and Speech Center, Ohio, according to the PubMed record; no funder is named there)

Summary

Probe-tube measurements in one wearer's ear of six assistive listening devices, including an infrared system, an induction floor loop and a personal amplifier used with a neck loop, comparing telecoil and direct coupling.

Key findings

  • The abstract's first two sentences identify the Madsen IGO 1000 and describe in-situ measurements of sample uniformity, volume-control linearity, ear-coupling effects on canal resonance and frequency-response differences.
  • Measured three samples each of six devices in the ear of one wearer: a Sound Plus infrared system, a Minicon induction floor loop, a Phonic Ear Phonear, a Radio Shack personal amplifier, and a Williams Sound PockeTalker used with an induction neck loop and wired directly.
  • The devices were generally uniform from sample to sample, although both PockeTalker versions varied in gain at all frequencies.
  • Devices coupled without a telecoil had broader, flatter responses than devices coupled through a telecoil, while the average differences between telecoil and non-telecoil coupling were minimal.
  • The earbud had almost no effect on the ear canal's resonance and lightweight headphones reduced it slightly; the authors conclude that probe-tube measurement is a feasible way to assess assistive listening devices on the wearer.

Limits

Read from the PubMed abstract only. One wearer, equipment of about 1990, and no listener outcomes; the abstract does not give the size of the frequency-response differences.

Read the original

doi.org/10.3109/03005369109079838

Link checked . We link to the original and do not host copies.

Cited in

Cite this source

Salzbrenner LG, Newman CW, Goldstein BA. Probe-tube measurements of ALDs: uniformity, linearity and frequency response differences. British Journal of Audiology 25(2):85-92. April 1991. https://doi.org/10.3109/03005369109079838 (accessed 13 October 2026).

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