The Bluetooth Special Interest Group announced LE (low energy) Audio and True Wireless Stereo (TWS) at CES in las Vegas, Nevada. TWS should encourage proliferation of TWS earbud solutions. LE Audio is the more noteworthy announcement, extending the breadth of the audio experience. This includes broadcast and multi-source streaming, shared listening and ability to grab feed from nearby TVs and monitors.
True Wireless Stereo
Bluetooth Classic is a single channel wireless protocol, because of this, both audio channels are transmitted to one earbud, one channel plays in the first earbud and the other is forwarded and played on the second earbud. Vendors have worked around forwarding, or to compensate for latency, between left and right channels in a variety of proprietary ways, typically locked-in to specific chipset or phone brands. Quality in this reconstructed stereo stream isn’t ideal– the forwarding earbud burns power in transmission, reducing battery life.
Version 5.2 of the Bluetooth Core specification introduces support for isochronous channels over Bluetooth Low Energy between the source (e.g. your phone) and the receivers (e.g. earbuds). Left and right audio channels are transmitted and picked up simultaneously: Quality at the earbuds is as good as it is at the source. Furthermore, an additional channel can be supported for voice control, coming back from earbud-microphone pickup. You can have simultaneous TWS and voice. While answering a call, your music can still play in the background, at reduced volume.
LE Audio is a new audio architecture built on isochronous channels to make Bluetooth audio an accessible tool. Audio quality is improved further through use of a new LC3 codec. Multi-source is supported, which means that you can connect to audio sources from a number of music playing mechanisms, switch from one source to another instantaneously, and allow any one of these to dominate while others are turned down but not silenced.
LE Audio supports audio sharing, meaning one device can broadcast the same high-quality isochronous streams to multiple sets of earbuds or other devices.
This isn’t just for personal audio sharing; it’s also for location audio sharing. Through multi-source and broadcast, you have the ability to connect with pop-ups to listen to audio feeds that may be muted at a venue (e.g. a bar, cinema, or flight status monitors in an airport).
This could be critical for those who are hearing impaired. These capabilities will enhance hearing aids to hear presenters, entertainment, and other sources more clearly in noisy environments.
Version 5.2 of the Bluetooth Core specification is now ratified. The LE Audio software framework is expected to be ratified a bit later this year. Products supporting LE Audio should start to be seen on the market early 2021.
Bluetooth Dual Mode and Bluetooth Low Energy
As with all new capabilities, there will be a transition from devices supporting only Classic Audio over Bluetooth Classic to newer devices supporting LE Audio. The primary sources of the audio (our devices) will have to adapt. In response, many implementations for earbuds and other listening devices will aim for dual-mode support to ensure backward compatibility, while also supporting the new features that LE Audio offers. Vendors and users are expected to switch quickly as momentum builds around these new capabilities.
CEVA provides Bluetooth connectivity solutions for both LE and dual mode (supporting Classic Audio and LE Audio). The company also provides voice pickup solutions, low power voice activity detection, multi-mic input and beamforming, AEC, ANC, and automatic speech recognition.
Published on Embedded Computing Design.