With the arrival of Bluetooth LE audio, we have gained new LC3 codecs, better audio quality and lower power consumption, but there is another feature that is not often mentioned, which is the "broadcast audio" that broadcasts audio streams from one audio source device to many audio receiving devices. To further standardize the use of this feature in the field of broadcasting and sharing, the Bluetooth SIG also named it under the trademark "Auracast".
To put it simply, Auracast is not much different from the audio broadcasting system we usually see, and it is also an audio experience with multiple transmissions, but because of the ubiquitous wireless connection method based on Bluetooth, Auracast is likely to become the most widely spread audio broadcasting technology to date.
Auracast's broadcast source, or transmitter, includes TVs, smartphones, tablets, laptops, or traditional public address devices, which stream audio to Auracast receivers, such as our TWS headphones or Bluetooth hearing aids. But the connection method is still different from our usual Bluetooth pairing, and there is also an Auracast assistant between the transmitter and receiver, which provides a UI interface on our smartphone or smartwatch to facilitate us to access Auracast broadcasts. The Bluetooth SIG also gives three ways to connect, such as searching directly like a Wi-Fi network, or scanning a QR code like Matter, and tapping the connection like a payment.
In the use cases given by the Bluetooth SIF, we can see that Auracast can be used in five application scenarios: hearing aids in public places, hearing aids at public counters, silent TV screens, tour systems and multilingual support, and the application places also cover multiple public places from movie theaters to transportation hubs. For example, high-speed rail stations and airports receive itinerary information at all times, enjoy their own docents when visiting scenic spots, and transmit multilingual dubbing at the same time in movie theaters.
This is not only a new audio experience for the average consumer, but also for the hearing impaired. The most difficult part of building hearing aid infrastructure for the hearing impaired is to achieve non-sensory connection in public spaces, and with the support of Auracast technology, hearing impaired people can benefit from Auracast devices, regardless of the severity of hearing loss.
Nick Hunn, chairman of the Bluetooth SIG Hearing Aid Working Group, mentioned that in 2013, the hearing aid industry began to contact them, wanting to create a standard solution to complete the wireless connection of hearing devices with other smart devices, thereby replacing the old remote sensing coil, because the latter not only has poor sound quality, but can only deploy one in a single area. Nick Hunn said that when they first developed this technology, there were only some collaborators of hearing device manufacturers, but as they began to add broadcast, low power consumption, low latency and other features, consumer electronics manufacturers also began to join in, and also wanted to integrate this technology into their products.
But at the same time, in order to ensure the interoperability of the Auracast ecosystem, related products must also pass certification to use this trademark. And for the creation of transmitters, broadcast audio is often a one-way process, and it is also necessary to make decisions independently, and it is impossible to know in advance how many Bluetooth devices receive transmission, nor is it clear about the actual capabilities of these Bluetooth devices, so the Auracast transmitter needs to transmit more information than a Wi-Fi access point, and the Bluetooth SIG has also given practical guidelines for deploying Auracast transmitters.
We have mentioned a variety of application scenarios such as hearing aids in public places, multilingual simultaneous interpretation, and personal audio sharing, which actually divides the types of Auracast transmitters, including public Auracast transmitters and personal Auracast transmitters. As its name indicates, public Auracast transmitters are mainly used in some public places, and the equipment forms are mainly commercial public address systems, televisions and large speakers, while personal Auracast transmitters are mainly used for small devices such as smartphones, computers and smart speakers.
There are also certain technical requirements for Auracast transmitters, such as all Auracast transmitters must be able to transmit 16kHz or 24kHz broadcast audio that is L3 codec, that is, standard quality public radio audio streams, but this does not mean that all Auracast broadcasts can only be limited to standard sound quality, and support for 48kHz LC3 high-quality public address audio streams is also allowed. For example, the personal Auracast transmitter mentioned above can transmit high-quality public radio audio streams by default.
Although a public broadcast audio stream is the most recommended form for public Auracast transmitters, for some conditional reception scenarios, such as meetings in hotels, you can also choose to encrypt the audio stream, so that access to Auracast broadcasts requires entering a specific broadcast code (Broadcast_Code) to complete decryption.
