Summary
A side-by-side guide to hearing loops, FM and infrared for large venues: how each works, how listeners connect, and the advantages and disadvantages of each.
Key findings
- The FM section (printed p. 4) describes connecting the transmitter to a public-address mixer to carry voice, music and recorded material. The infrared section (printed p. 6) describes an emitter converting the base-station signal into invisible infrared light, received by a photosensitive cell on the listener's receiver.
- The opening explanation describes an assistive listening system as capturing sound near its source, carrying it to the listener and coupling it through earphones or a hearing device to reduce the effects of distance, noise and reverberation. The technology list (printed p. 2) expands FM as frequency modulation; the loop section describes telecoils in hearing devices or separate receivers, and the FM section describes a transmitter feeding receivers tuned to the same channel.
- The FM and infrared sections explain that a neckloop is a small wire loop worn around the neck, converting a receiver's electrical output into a magnetic signal for a telecoil. The infrared section distinguishes the base-station transmitter, the emitter that produces infrared light and the light-sensitive receiver, and describes line-of-sight paths and shadows caused by obstructions.
- Explains that listeners with telecoils need no borrowed receiver in a looped room, while FM and infrared require every listener, with or without hearing aids, to borrow a receiver used with earphones or a neckloop.
- Lists FM's advantages: highly portable, easy to install with the lowest installation cost (FM advantages, page 5), easy coverage of very large seating areas, several channels for adjacent rooms, translation and audio description, and use indoors or outdoors.
- Lists FM's disadvantages: receivers for everyone; signals that pass through solid surfaces, so it is unsuitable where privacy matters (encrypted digital systems exist for that); possible radio interference; and receivers the venue must clean, issue, collect and keep charged.
- Describes infrared as carrying audio on 2.3 MHz and 2.8 MHz subcarriers, normally free of radio and electrical interference, able to run several channels at once, and usable where confidentiality matters because the signal does not pass solid surfaces, provided windows are covered.
- Lists infrared's disadvantages: receivers for everyone, so listeners must draw attention to themselves to borrow one; impractical outdoors because of sunlight; line of sight to the emitters, so enough emitters must avoid shadows from columns and seats; and more cost and difficulty for very large areas such as stadiums.
- Lists loop disadvantages as well: spill into adjacent rooms from perimeter loops (much less with phased arrays), installation that can be difficult, an unencrypted signal, a single channel, and electromagnetic interference picked up by telecoils, which it notes also affects neckloop users of FM and infrared.
- Describes the US FM bands as 72-76 MHz, older and subject to interference, and 216-217 MHz, newer and intended for auditory assistance only.
- Lists as an infrared advantage that several channels, such as several languages, can run at once without interfering, and as a disadvantage that facility owners must maintain, clean, issue and collect receivers and keep their batteries charged.
Limits
Expert guidance, not a study: no measurements or references are given. First written in 2006 and revised by the author in 2015; this copy is HLAA's reprint dated 28 October 2021, so it predates Auracast and says no large-area systems broadcast over Bluetooth. It is distributed by HLAA's hearing loop program. Its description of 216-217 MHz as for auditory assistance only is narrower than the FCC rules, which share the band with other uses.
Read the original
www.hearingloss.org/wp-content/uploads/comparison-of-large-area-assistive-listening-systems.pdf
Cited in
- Which hearing devices can receive which systems?Open
- Auracast, hearing loop, infrared, RF or Wi-Fi: which suits which room?Disputed
- How many receivers and neckloops does each code require, and how should a loan pool be run?Partly answered
- How many listeners carry a telecoil, an Auracast-capable device or a smartphone?Disputed
- What do listeners prefer, and how often do they use venue systems?Partly answered
- Where do hearing loops fall short: metal, spill, noise and upkeep?Partly answered
- Where does infrared assistive listening work, and where does it fall short?Partly answered
- Which radio bands can venue FM and RF systems use, and what limits them?Partly answered
- What does each system cost to install and to run over its life?Open
- What works in places of worship, and what do the rules ask of them?Partly answered
- What reaches a cochlear implant user in a venue, and how well?Partly answered
- Do neckloops give telecoil users good sound from FM, infrared, Wi-Fi and Auracast receivers?Not reliable yet
- What works in courtrooms, council chambers and other meeting rooms where speech must be heard by all and kept in the room?Partly answered
- Can venue broadcasts be spoofed, hijacked or jammed, and what protects them?Partly answered
Cite this source
Compton-Conley C. Comparison of Large Area Assistive Listening Systems. Hearing Loss Association of America (reprint). 2015. https://www.hearingloss.org/wp-content/uploads/comparison-of-large-area-assistive-listening-systems.pdf (accessed 14 October 2026).
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