Auracast glossary: the words you will meet

Auracast. The Bluetooth SIG's brand name for broadcast audio over Bluetooth LE Audio. A trademark; products that use the name on the box have passed the SIG's qualification. This site uses it the way everyone else does, to mean the feature.

LE Audio. The 2022 generation of Bluetooth audio, built on Bluetooth Low Energy rather than the older Classic radio. It covers ordinary one-to-one streaming (unicast), broadcast (Auracast), the LC3 codec, and hearing-aid support. A device can have LE Audio without broadcast.

Classic Bluetooth, A2DP. The audio Bluetooth you have used since 2004. One source, one listener, pairing required. Still used for calls and music by every current pair of earbuds; Auracast is an extra mode, not a replacement.

Source, broadcaster, transmitter. The thing that sends. A TV, a dongle, a venue rack unit, a phone.

Receiver, sink. The thing that plays. Earbuds, headphones, hearing aids, a speaker, or a receiver box with a headphone socket.

Assistant. The thing that finds broadcasts and tells the receiver which one to join. Usually a phone. Some hearing-aid apps carry one, which is how they work on an iPhone. Some receivers have their own and need no phone.

Stream, BIS. One audio channel inside a broadcast. The standard's name is broadcast isochronous stream. A venue transmitter typically carries two, so it can send a second language or audio description.

Broadcast code. The password on an encrypted broadcast. Delivered as text on signage or inside a QR code.

Scan-to-Listen, Broadcast Audio URI. The SIG's 2025 standard for putting a broadcast's name and code into a QR code or NFC tag. Scan it, and the phone joins.

LC3. The LE Audio codec. Same quality as SBC at about half the bit rate; runs at 16, 24 or 48 kHz. All Auracast broadcasts use it.

Latency. The delay between the source playing a sound and you hearing it. Venue transmitters under 40 ms; consumer dongles 50 to 120 ms.

Auracast-ready. Marketing for "the radio can do it and the firmware does not yet". Sennheiser's Momentum True Wireless 5, Phonak's Infinio and Signia's MaX all shipped this way. On this site that is the status Firmware pending, with the promised date recorded.

Telecoil, T-coil. A small coil in a hearing aid that picks up the magnetic field from an induction loop. Still in most hearing aids. Nothing to do with Bluetooth, but central to the loop question.

Induction loop, hearing loop. A wire around a room carrying the PA signal as a magnetic field for telecoil hearing aids. The forty-year-old system Auracast is slowly joining, and one day replacing.

Neckloop. A loop you wear, driven by a receiver, so that telecoil hearing aids can hear a broadcast.

Assistive listening system, ALS. The venue-side category: loops, infrared, FM, and now Auracast.

Audio sharing, Audio broadcast, Shared audio. What Google, Samsung and Microsoft respectively call their versions. Google's and Samsung's are Auracast. Microsoft's sends to exactly two paired headsets and is not an open broadcast.

Qualification, SIG listing. The Bluetooth SIG's product directory lists every qualified Auracast product and its roles (transmitter, receiver, assistant). A listing is one of the three kinds of evidence we accept for the status Works today; how we test explains the other two.

PoE, Dante. Power over Ethernet and the audio-over-IP standard. Both appear on the spec sheets of venue transmitters, which is where the venue guide picks up.