Summary
A hearing-technology maker's patent on a coupler with several inductors for hearing aid telecoils, whose background describes the limits of neck loops and silhouette inductors.
Key findings
- States in its background that neck loop and silhouette couplers have had difficulty giving the telecoil a field "of sufficient strength and sufficient uniformity" for typical positions, so that coupling is predictable, loud enough and able to overcome environmental magnetic noise.
- States that silhouette couplers, designed with behind-the-ear aids in mind, have not reached sufficient field strength at the greater distance to in-the-ear telecoils, or given the right field orientation for best coupling.
- Gives typical office magnetic noise as in the 5 mA/m range and a cellular phone as about 30 mA/m at three feet, as examples of interference that telecoil pickup must overcome.
- Proposes separate inductors shaped for in-the-ear and behind-the-ear aids, with signal conditioning, to give a stronger and more uniform field.
Limits
Background text in a patent, written to motivate the applicant's own design: it gives no measurements of particular neck loops or silhouettes. Priority date 7 January 2000, filed 31 January 2003, granted 29 August 2006. The text was read through Google Patents; the link given is the USPTO's copy.
Read the original
image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/7099486
Cited in
- Do neckloops give telecoil users good sound from FM, infrared, Wi-Fi and Auracast receivers?Not reliable yet
Cite this source
Julstrom SD, Drambarean V, Soede W. Multi-coil coupling system for hearing aid applications (US 7,099,486 B2). United States Patent and Trademark Office. 29 August 2006. https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/7099486 (accessed 10 October 2026).
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