Summary
A European standards report describing hearing loop systems for spectrum regulators: their field strength, how fast the field falls outside the loop, the standards that apply, the size of the market and its view of Bluetooth Low Energy as an alternative.
Key findings
- Clause 3.1 defines a telecoil as a magnetic pickup coil, a hearing instrument as a hearing aid or cochlear implant, and a hearing loop listener as a portable receiver giving audible output from the loop signal. It defines a hearing aid as a worn personal amplification system and a cochlear implant as a device stimulating the auditory nerve through electrodes in the cochlea, allowing some people with severe hearing loss to perceive sound.
- Clause 3.1 defines a hearing loop system as signal sources and amplifiers creating magnetic fields through audio-frequency current in a loop or coil; a perimeter loop follows the coverage boundary horizontally, while a phased array uses overlapping loops with currents of different phase for more even coverage and less spill. It also defines a magnetic field strength meter and gives 400 mA/m as the 0 dB reference.
- Clauses 5.1.1 and 5.1.2 describe the loop driver supplying current and the magnetic field level at listening positions, including its variation with audio frequency. Clause 5.1.3 explains that the magnetic field extends beyond the intended coverage space and that counter and help-point loops serve a very local area.
- Clause 5.1.0 (printed p. 9) describes selecting a hearing instrument's T position or programme to receive a loop through its telecoil; it explains that the T input can be assigned to a user-selectable programme operated by a push-button. A physical T-labelled switch is therefore one possible control, rather than a requirement of the coupling method.
- Clause 5.1.0 (printed p. 9) also describes an amplifier producing audio-frequency current in the loop cable, and identifies counter and fixed help-point systems as small-area loops covering a localized space. These passages support the loop-driver and counter-loop definitions.
- Describes loops as purely magnetic, unmodulated audio-frequency systems working between 10 Hz and 9 kHz, and says no cases of radio interference from them have been reported.
- Says a loop meeting IEC 60118-4 has a frequency response within ±3 dB of 1 kHz from 100 Hz to 5 kHz, and a field that varies by no more than ±3 dB over a large area system or ±8 dB for a small area system such as a counter loop.
- Shows the vertical and horizontal field components moving away from a perimeter loop, notes that the vertical component, at right angles to the loop's plane, is the one most hearing aids use, and says the field usually falls to -30 dB (re 400 mA/m) at one loop width and -44 dB at twice that distance; field strengths below -40 dB are generally accepted to be inaudible to hearing instruments.
- Where even weak fields outside the room are unacceptable, such as for confidentiality, says low-spill amplifiers with pairs of phase-shifted loop arrays are used to cut the overspill sharply.
- Estimates UK sales at no fewer than 10,000 loop systems a year and the UK installed base at 50,000 to 200,000 systems.
- States in its executive summary (clause 5.1.0) that "Emerging technologies such as Bluetooth® Low Energy do not offer a practical alternative to HLS in most cases due to practical problems such as latency, the need to pair, and short battery life", and that even if these problems are solved, the very large installed base of hearing instruments with telecoils will benefit from hearing loop systems for many years.
- The small-area field figure is in clause 5.1.2. Reference [i.2] and clause 5.1.5.2 identify IEC 60118-4:2014 without citing Amendment 1 (2017); this report therefore does not establish what the amended small-volume acceptance clause says.
- Clause 5.1.1 explains that hearing loops have no carrier or modulation scheme and require a magnetic-field response of 100 Hz-5 kHz within ±3 dB of the 1 kHz response. It explicitly allows extension above 5 kHz within the report’s 9 kHz scope; 5 kHz is not described as a physical cutoff of every loop.
Limits
A spectrum-planning document rather than a performance study: its spill figures come from one illustrative plot without stated loop size or measurement method, and its market figures are estimates without sources. Its statement on Bluetooth Low Energy gives no evidence and dates from January 2022 or earlier. It records that no comments were received at enquiry. The document shows January 2022 as its publication month.
Read the original
www.etsi.org/deliver/etsi_tr/103600_103699/103614/01.01.01_60/tr_103614v010101p.pdf
Cited in
- Auracast, hearing loop, infrared, RF or Wi-Fi: which suits which room?Disputed
- Will equipment bought today meet the standards that follow?Open
- Can Auracast serve ticket windows, service counters and reception desks?Open
- Where do hearing loops fall short: metal, spill, noise and upkeep?Partly answered
- Do portable and counter loops work, and how should they be set up and used?Partly answered
- How good is the sound each system delivers: bandwidth, codecs and speech understanding?Partly answered
Cite this source
ETSI Technical Committee ERM. ETSI TR 103 614 V1.1.1: Electromagnetic compatibility and Radio spectrum Matters (ERM); Hearing Loop System (HLS) intended to assist the hearing impaired in the frequency range 0 Hz to 9 kHz; System Reference Document. European Telecommunications Standards Institute. January 2022. https://www.etsi.org/deliver/etsi_tr/103600_103699/103614/01.01.01_60/tr_103614v010101p.pdf (accessed 14 October 2026).
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