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Bluetooth spec’s design journey from Classic to LE Audio

Bluetooth technology has become the immediate solution for most wireless audio streaming applications. If you are a wireless music listener using a headset or your car has an infotainment system, there is a good chance that you are using Bluetooth technology.

Bluetooth Classic (BR/EDR) is the principal radio in current audio wireless applications. Initially, the BR/EDR audio profiles supported mono audio voice calls. However, with personal listening popularity, Bluetooth developers are now stretching the current Bluetooth audio standard to its limit.

Not surprisingly, therefore, the 2020 Low Energy (LE) Audio is considered the next-generation Bluetooth audio. It defines a new approach or architecture to satisfy multiple requirements such as low power consumption, smaller devices, and lower latency to support the next 20 years of wireless audio innovation.

Bluetooth LE Audio allows developers to build the same types of products based on the Classic audio standard. Still, it introduces four critical new features that focus on improved performance and support for new innovations. These four key features are Low Complexity Communications Codec (LC3), highly synchronized left and right audio streams, standardized hearing aids, and point-to-point communications.

  1. LC3

Low Complexity Communications Codec (LC3) replaces sub-band codec (SBC) with a more efficient and higher quality technology. As the new standardized Bluetooth implementation, LC3 addresses the limitations of the current BR/EDR standard and SBC technology. To incorporate into any Bluetooth audio profile, LC3 can encode music and speech at various bitrates (Figure 1).

Figure 1 Using listening tests, the audio quality of LC3 exceeds SBC. Source: Bluetooth SIG

  1. Synchronization

Bluetooth Audio LE supports independent, highly synchronized left and right audio streams for multi-stream and true wireless stereo (TWS) earbud applications.

  1. Hearing aids and earbuds

The technology enables true global interoperability by supporting the development of standardized Bluetooth hearing aids. Bluetooth LE latency is much lower than the Bluetooth Classic. The time it takes to do the encoding is typically about 10 milliseconds. This means that if an individual sends something over a Bluetooth link, it gets to the listener almost as fast as the standard sound does without listening devices.

It’s useful if a listener has a hearing aid while listening to a television and a second individual does not have a hearing loss. In this scenario, the sound arrives at the same time to a hearing impaired individual as it does to the second individual (Figure 2).

Figure 2 With Bluetooth LE, wireless hearing devices remain in sync with the external events. Source: Nordic Semiconductor

  1. Point-to-point communication

LE Audio will continue to support point-to-point communication and add a new broadcast feature that supports an unlimited number of synchronized audio links. LE Audio also includes private or public broadcast support.

LE Audio playing field

There are numerous applications for this technology. Audio streaming is the obvious one. Next, automotive OEMs are integrating this Bluetooth technology into vehicle’s audio and multimedia systems. Low energy consumption, low latency, and quick connection set-up speeds also make LE Audio a prominent feature in wearable designs.

Bonnie Baker is a seasoned analog, mixed-signal, and signal chain professional and electronics engineer. She has published and authored hundreds of technical articles and blogs in industry publications. Baker is also the author of the book “A Baker’s Dozen: Real Analog Solutions for Digital Designers” as well as coauthor of several other books.

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