LE Audio is the future of wireless sound

By Vince Hagen, Business Development Manager, Nordic Semiconductor

This article originally appeared in the November'24 magazine issue of Electronic Specifier Design – see ES's Magazine Archives for more featured publications.

It was around the turn of the century that the first Bluetooth wireless headsets arrived on the market, and within five years consumers had fully embraced the tech. The embrace of headsets formed the first wireless audio revolution, but now we are entering the second with the commercial introduction of Bluetooth LE Audio (LE Audio).

In 2020 the Bluetooth Special Interest Group (SIG) announced a new specification that included a high quality, low-power audio codec (the Low Complexity Communications Codec or LC3) that promised to bring higher quality and longer battery life to wireless sound. Since then, the road to commercialisation has proved technically complex and has taken time, but it hasn’t been unusually protracted.

The LE Audio and Auracast difference

While Bluetooth LE supports multiple communication topologies for data transfer, it only facilitates point-to-point communication for audio streaming. Today’s wireless earbuds only receive a single stream of audio and require an engineering work around to retransmit a second channel to the other earbud, at the cost of processing power and battery life. In contrast, LE Audio’s multistream audio functionality enables multiple devices to receive their own unique audio stream. The left and right channels retain the original precise musical timing upon replay. The result is excellent and true stereo sound, and, because no additional processing is needed at the earbuds, battery life is extended.

It is difficult to quantify reduction in power consumption between LE Audio and Classic Audio because much depends on both implementation and product use. For example, product developers focused on providing the highest audio quality might choose to implement the LC3 codec for hi-fidelity rather than aiming for significant battery life extension. Others may choose to focus entirely on extending battery life by trading-off sound quality. In the latter case, focusing solely on maximising battery could see the run time of earbuds or a Bluetooth speaker as much as double compared to Classic Audio.

Another breakthrough feature of LE Audio is the addition of Auracast broadcast audio. Auracast allows an audio source device such as a smartphone, laptop, TV, or sound system to broadcast one or several audio streams to an unlimited number of Bluetooth audio receivers. There are several potential use cases for Auracast, but chief among them is the ability for it to become a high quality, lower cost augmented and assistive listening technology in venues where public address (PA) or hearing loop (also known as telecoil) infrastructure is currently deployed. Such a use case opens up wider accessibility for the over 1.5 billion people living with hearing loss around the world. Auracast can also enable multi-language audio streams in locations that support simultaneous translation services.

Next gen SoCs optimised for LE Audio and Auracast

While LE Audio’s LC3 codec requires significant computational resource to compress and decompress audio, the latest generation of efficient wireless SoCs can comfortably meet this requirement without significant power consumption drawbacks.

For example, Nordic Semiconductor’s new nRF54H20 SoC features multiple Arm Cortex-M33 processors and multiple RISC-V coprocessors all optimised for specific types of workloads. This will provide ample overhead to supervise the computational demands of advanced audio codecs such as LC3 while simultaneously looking after the ultra-low power wireless connectivity between source and receiver. The computational power, high efficiency, and level of integration of the Nordic SoCs also ensures tomorrow’s LE Audio solutions will offer better audio quality, consume less energy, be more compact, and quicker to bring to market.

Nordic Semiconductor’s nRF54H20 SoC features multiple Arm Cortex-M33 processors and multiple RISC-V coprocessors with ample overhead to look after the computational demands of advanced audio codecs

For Auracast to reach its full potential, wireless chips will also need to support multiple audio streams. Theoretically, the number of audio streams is unlimited, however not all SoCs are created equal. Nordic’s nR54H20 SoC has been engineered to maximise the potential of LE Audio. The SoC includes two Time Division Multiplexed (TDM) Audio Interfaces that enable multiple channel audio data transfers on a single data line. This means the chip can support multiple audio streams from a range of sources such as a TV, microphone, PA system and so on, or enable broadcasts in multiple languages. The multi-language capability provides venues such as museums with a cost-effective, and hygienic alternative to handing out infrared, FM, or wired headsets to visitors in need of translation services. Instead, visitors can use their own Auracast-enabled Bluetooth earbuds or hearing device.

These innovations aren’t mainstream just yet, but they will be soon, and when they are the future of wireless sound will be here.