What is Bluetooth Auracast?


Bluetooth® LE Audio is the next generation of wireless audio streaming, with many innovative features to enable a whole new range of market and product creation opportunities for forward-thinking companies.


From hearing aids and wearables for augmented and virtual reality offering greater intelligibility and longer battery life, public information systems offering simultaneous announcements in multiple languages, to the reimagination of live entertainment, LE Audio fundamentally redefines wireless audio streaming experiences.



Amongst many new innovative features, LE Audio adds support for Auracast™️ broadcast audio, a new feature that enables an audio source device to broadcast an audio stream to an unlimited number of Bluetooth audio sink devices. Audio broadcasts can be open, allowing any in-range sink device to participate, or secured, where only those sink devices with the correct pass key can participate.


Auracast will deliver life-changing audio experiences, enhancing the way we engage with others and the world around. Auracast will enable new audio experiences that will help our world sound better. Auracast will allow us to invite others to share in our audio experiences, helping bring us closer together. When using our wireless earbuds to listen to a song or movie playing on our smartphone, tablet, or laptop, Auracast will allow family or friends to join in and listen using their own Auracast-enabled Bluetooth earbuds or hearing device.




Auracast will enable us to fully enjoy televisions in public spaces, unmuting what was once silent and creating a more complete watching experience. Silent televisions in public venues like airports, gymnasiums, restaurants, and waiting rooms will be able to broadcast audio that any visitor with Auracast-enabled Bluetooth earbuds or hearing aids will be able to hear. 


When visiting a public location such as a transit centre, cinema, conference centre, concert venue, house of worship, and more, we will be able to receive audio broadcasts from the public address (PA) system directly into our Auracast-enabled Bluetooth personal audio devices such as earbuds or hearing aids. When used in this manner, Auracast broadcast will function as the next-generation assistive listening system (ALS) technology.


Auracast Broadcast Isochronous Streams (BIS) are termed Connectionless in that they do not include control channels to allow acknowledgements from sink devices back to the source device. A source device operating in Broadcast mode has no information about how many of a potentially unlimited number of receiving sink devices are subscribed to a BIS. Broadcasts can be configured to be open for any sink device to subscribe, or secured with a pass key to protect against unauthorised access.


Auracast uses the concept of Advertisements to enable transmitting sources to announce the existence of their audio streams. Receiving sink devices utilise a Broadcast Assistant to scan for the presence of a broadcast audio streams via these Advertisements. In typical use cases, this Assistant will be an app on a mobile device that is paired to the receiver to allow the user to select from multiple streams, adjust volume levels, and decrypt private audio streams using a pass key, perhaps supplied by a venue or included in the purchase of a ticket for an event.



Multiple BIS streams can be grouped together. The Broadcast Audio Source Endpoint (BASE) structure is a three tier hierarchy with the individual BIS streams as the bottom tier. At the middle tier, BIS streams with common features such as the left and right channels of a stereo pair are contained in Subgroups. The Subgroups are then aggregated into a Broadcast Isochronous Group (BIG) at the top tier.


This is the beginning of a new wireless audio paradigm and an opportunity to create the enabling products that will many aspects of our lives. As a Bluetooth SIG Adopter Member and an active participant in the development of LE Audio technology applications,


Inline Audio is well placed to help companies gain a first mover advantage in the emerging market for Auracast and other LE Audio products. With our mutual non-disclosure agreement policy, companies can talk in confidence about realising this next generation of wireless products leveraging LE Audio technology.


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