Available for digital download, this new book from Nick Hunn, Chair of the Bluetooth SIG Hearing Aid Working Group, Vice Chair of the Generic Audio Working Group, and a key contributor to the LE Audio specifications, provides an in-depth, technical overview of the LE Audio specifications, illustrates how they work together, and shows you how to use them to develop innovative new applications.
The following is an excerpt from Hunn’s book that looks at the some of the applications LE Audio will support.
Chapter 12. Bluetooth LE Audio Applications
The whole point of developing Bluetooth® LE Audio was to support new audio applications, not just to produce a slightly lower power alternative to the existing Bluetooth Classic Audio profiles. Part of that was driven by the need to catch up with proprietary extensions, particularly for True Wireless Stereo. The bigger prize was to allow innovation in audio, to keep up the momentum which TWS and voice assistants had generated, making audio more universal and allowing greater flexibility in how we can listen to it.
Broadcast is the child of the telecoil. The telecoil system has been around a long time. It performs well, but it is remarkably basic. It is mono, has a very limited audio bandwidth, and you can only hear it if you’re located within the confines of the inductive loop. Whilst the aim of Bluetooth technology was to provide a more capable successor, it very quickly became obvious we could expand significantly on the user experience of telecoil.
An initial concern with replicating the telecoil experience is that a Bluetooth transmission is not confined by its installation area. Being wireless, it penetrates walls, meaning that people in adjoining rooms and spaces can also hear any broadcast audio. In many situations, such as public halls and places of worship, that’s not a significant problem, because the only source of broadcast audio will be the one that is relevant for that particular venue. However, in other situations, such as TVs in hotel rooms, or systems within conference centres with multiple meeting rooms, that becomes a major issue, as broadcasts will overlap, with the result that people will have difficulty in understanding which broadcast is the one they want to connect to, and potentially hearing things which they shouldn’t.
That led to the implementation of encryption within a broadcast stream, so that only a user with the correct Broadcast_Code to decode that stream is able to listen to it. Although the broadcast streams overlap, the Broadcast_Code provides an access mechanism where only authorised listeners can decode a particular broadcast Audio Stream. That’s akin to how WiFi works today, where users are given an SSID name to identify a particular Wi-Fi network, and then need to key in an access code to be allowed to connect to it. Whilst people have become used to doing that with Wi-Fi, it’s a pretty basic and often frustrating user experience. Everyone wanted Bluetooth® LE Audio to do it better.
Tackling that needed a better mechanism for a user to access the code than a scrap of paper on a coffee shop table or a notice on the wall. It led to the development of the Broadcast Assistant and the Commander, providing ways for that information to be sent from a Broadcaster that is trusted or known to an individual listener. As the specifications developed, it quickly became obvious that this provided a very powerful mechanism for users, both to pick up broadcast codes, and gain access to individual broadcasts in a far more flexible manner than we have ever seen with previous Bluetooth connections.