Many have noticed the announcement of LE Audio at the beginning of 2020. We summarize the main features, and, yes, there are reasons to get excited.
What’s going on today?
Before we delve into what’s coming, we look at the current status of audio over Bluetooth.
Bluetooth is by far the most recognized wireless standard for audio transmission, with an estimated 1 billion listening devices shipped in 2019 alone. With source devices coming in addition, we are talking about an enormous market which is foreseen to further grow. Bluetooth audio is utilized extensively in earbuds, headsets, wireless speakers, laptops, tablets, and cars, and the number of use cases is growing by the day.
However, the vast majority of these solutions are based on Bluetooth Classic (BR/EDR). This specification consumes more power compared to Bluetooth LE and is not specifically tailored towards audio use cases. Consequently, vendors have added custom, unstandardized features on top, creating value only for a subset of users.
Read more: The evolution of Bluetooth audio
With the new specification, Bluetooth Audio will have two modes of operation, namely “Classic Audio” over BR/EDR as most are familiar with, and “LE Audio.” Besides being based on the well-established Low Energy standard, let’s look at what LE Audio brings to the table.
Support for more advanced use cases
The most significant change from a user perspective is support for new audio sharing features. In its pure form, Bluetooth Classic Audio is a point-to-point stream, implying that one audio source, such as a phone, can only stream audio to a single headset. Some vendors have provided custom solutions on top, so two individual headsets, for instance, can connect to the same source. However, as this is vendor/implementation-specific, it is often required that the source and both headsets are from the same vendor.
LE Audio introduces a new feature named Audio Sharing, which addresses this issue within the standard. On a personal level, it allows users to share audio to multiple sinks from a single source, allowing people to watch the same movie on a tablet while listening on separate headsets. There is also a location feature where a public source, such as a TV in a waiting area, can send audio to numerous headsets or hearing aids, enabling quieter common areas with personal listening experiences.
A new audio codec as standard
The primary purpose of an audio codec is to reduce a raw audio stream of e.g., CD-like quality, which is roughly 1400 Kbps down to something more manageable to transmit over the air, such as 150-350 Kbps. The stream is then decompressed at the headset side before playback.
Although Bluetooth LE can handle much higher data rates, reducing airtime conserves power, provides resilience to interference, and improves co-existence with other devices.
With the new specification, LC3 (Low Complexity Communication Codec) is introduced as the standard audio codec instead of SBC. This codec promises to deliver the same quality audio at reduced bitrates.
Built-in support for untethered earbuds
In Bluetooth Classic Audio, the data stream contains both the left and right channels. Producers of untethered earbuds then have to get creative to support two audio sinks, each playing back their respective channel. This is sometimes accomplished by receiving the stereo stream over Bluetooth Classic on one earbud and using another means of transmission, such as magnetism, to send one audio channel on to the other earbud.
Numerous great solutions have been created using such a design, but it adds layers of unwanted complexity and limitations. LE Audio supports Multi-Stream with accurate synchronization, paving the way for untethered earbuds, supporting a single-channel stream to each unit with synchronized playback.
Exciting times ahead
The new LE Audio standard is an exciting release, with features impacting positively across the globe. Nordic Semiconductor is working towards providing great hardware and software for the best experience with LE Audio.