Bluetooth LE Audio is the latest addition to the scores of Bluetooth standards, and this new feature aims to bring higher quality, seamless listening to devices while also dropping battery use. It’s designed for a hyperconnected future where we no longer rely on just our smartphones, laptops, or other similar devices — but on lots of different devices, all at once.
Bluetooth has been around for over two decades, but the early application of Bluetooth for audio was limited to answering calls with audio headsets and in-car sets. The category saw a sharp and spontaneous upswing with Apple’s decision to banish the headphone jack from the iPhone 7, swiftly followed by the introduction of the Apple AirPods to knock more wires further away from our ears.
The global Bluetooth audio market was estimated to be valued at $18.8 billion in 2020 and is projected to reach $41.1 billion by 2027. As the industry grows, we can expect further sophistication in Bluetooth audio technology, allowing for more affordable products, better audio quality, and longevity. Bluetooth LE Audio is a step toward more efficient audio products, so expect to see it expand more and more in the coming years. Here’s what Bluetooth LE Audio is, and how it might change our lives.
Bluetooth LE Audio is based on a formerly popular Bluetooth standard — Bluetooth LE (Low Energy). As the name suggests, Bluetooth LE allows Bluetooth devices to communicate while consuming minimal energy. Bluetooth LE is typically used for devices such as smartwatches, medical equipment, IoT devices like smart weighing scales or air purifiers, smart trackers like the Apple AirTag, and other wellness equipment. The 12-year-old standard, however, does not transmit audio and, therefore, cannot be used with audio equipment, earbuds, and other Bluetooth headsets.
Bluetooth LE Audio, on the other hand, is a much newer standard that was announced in 2020 by the Bluetooth Special Interest Group (SIG) along with specifications for Bluetooth 5.2. As the suffix “Audio” warrants, the standard is intended for transferring audio over a low-energy Bluetooth connection, which wasn’t possible before.
Besides its primary benefits of more energy-efficient Bluetooth audio streaming, the standard also allows for multiple connections with a single device while improving audio quality significantly over a standard Bluetooth connection. The most prominent advantages of Bluetooth LE Audio are discussed below:
First of all, Bluetooth LE Audio allows multiple connections on all supported devices. Imagine this as an IoT network of Bluetooth-based audio devices where every device can communicate directly with the others — with the correct permissions — and constantly exchange tasks per requirement. For instance, when you use a headset with a smartphone or a laptop, the audio reception restricts you to the area in which Bluetooth signals can still be received. This area is around 10 meters (about 33 feet) for most audio devices.
Imagine your headset connecting simultaneously to two sources — a smartphone and a tablet — for streaming podcasts from an online service. Both devices are in different rooms of your house. The audio is transmitted from the smartphone to your headset when you are close to your smartphone. But, when you decide to move to another room, the smartphone communicates with the tablet to take over, and your headphones automatically switch to an audio stream transmitted by the tablet. All of this happens so seamlessly you barely notice any lag or disconnection in between. In the future, the smartphone and tablet could simply be replaced by multiple transmitters spread across the house, workplace, or public area.
Bluetooth LE Audio deploys the philosophy of “multi-profile by design.” It identifies the different connections a user has and automatically switches between those connections based on ad-hoc requirements. The future may also include “broadcast assistants”, a device that can act as a bridge and improve the range of the connection to an original device, much like Wi-Fi extenders today.
Besides using your earphones or Bluetooth device with multiple input sources, Bluetooth LE audio also makes way for a single source to connect to multiple output devices.
A prominent benefit of Bluetooth LE Audio is it allows extremely low latency audio transmission. In normal Bluetooth audio transmission, the source sends audio signals to a device, which decides how to render the audio signal. Bluetooth LE Audio addresses this by learning the time required to transmit signals at the source itself. When a receiver device is not in use, a sender device can completely turn off that audio stream, reducing energy consumption.
Bluetooth LE Audio can accomplish this by forming a spatial map of all the other Bluetooth devices present in its vicinity and only sending signals when needed. For instance, while playing audio on a stereo speaker setup, the source can turn off signals to the left speaker momentarily when sound output is only required on the right speaker (even for a few seconds) instead of sending a silent signal to the left speaker. Bluetooth LE Audio can also send separate signals to the left and the right, instead of sending a mixed signal to the receiver, which would then split it into the left and right channels.
In addition to faster and more energy-efficient audio signal transmissions from multiple sources to the receivers, Bluetooth LE Audio can also have significant applications in other areas. Some of the applications where Bluetooth LE Audio makes a considerable difference are:
Applications in hearing aids
The new Bluetooth standard is capable of revolutionizing how hearing aids work. Just like multiple streaming sources for a standard Bluetooth headset, we may also have specialized transmitting devices in the future to assist people with hearing difficulties. These special transmitters may automatically amplify all public announcements and ambient sounds for people using hearing aids, thereby helping them hear and experience the auditory world the same way as people without hearing difficulties.
Imaginably, that also comes with problems. In the future, a person with hearing aids may come across multiple sources broadcasting their audio, demanding users manually tune for specific announcements, while also controlling the volume to match their natural hearing ability. Bluetooth SIG proposes to rectify this with the help of another device known as a commander. The commander can be anything from a specific app on a smartphone, or one of the options in a phone’s Bluetooth settings.
Google is making an essential step in this direction by adding support for Bluetooth LE Audio to Android. In December 2021, Esper’s Mishaal Rahman dug up changes in the Android source code hinting support for Bluetooth LE Audio to be added to the final release of Android 13.
A few months later, Google officially added support for low-energy audio broadcasts with the second beta of Android 13. As per Esper, the change nearly confirms that Android 13 will allow smartphones to “broadcast media to devices near [them], or listen to someone else’s broadcast.”
Broadcasts and augmented reality
Even for people with no hearing disability, Bluetooth LE Audio can be useful, especially for keeping in tune with public broadcasts. Imagine hearing train announcements without needing to remove your headset, or listening to any public park entertainment. It’s effectively like an FM radio service, but heavily reliant on 5G and future mobile internet technologies.
At some point, we could see Bluetooth LE audio augmenting restaurant and coffee shop experiences, allowing customers to choose from various audio tracks based on their mood, instead of a piece of standard background music.
In addition, Bluetooth LE audio can significantly impact the adoption of public augmented reality (AR) experiences where a group could share an experience through a common broadcasting source.
In June 2022, the Bluetooth SIG announced a new standard called Auracast for shared audio experiences. Auracast, previously known as Audio Sharing, will allow a single transmission source, such as a laptop or a TV (or a public announcement system for a much larger audience), to broadcast audio to multiple recipients directly into their earphones, headphones, or hearing aids. Auracast might eventually replace traditional announcement or vast stereo systems — such as in movie theaters – with personal headsets with Bluetooth LE Audio enabled. Such a change will improve speech recognition for not only people with hearing disabilities but also for anyone who desires more clarity in audio in any given public setting.
For users, the standardization of Auracast means they will be able to know about different audio broadcasts — pretty much how nearby Wi-Fi networks are visible — and choose any one of the streams at their discretion.
Besides hearing aids, remote controls are excellent candidates for devices that can benefit significantly from Bluetooth LE Audio. Currently, TV remote controls with embedded microphones for voice commands have to rely on classic Bluetooth transmissions. As a result, voice commands are jittery on most non-premium Android TVs, but this is something Bluetooth LE Audio could resolve by providing faster and more efficient data transmission.
Alongside the energy efficiency of Bluetooth LE Audio, one of its essential characteristics is the new Low Complexity Communications Codec (also known as LC3). The LC3 codec was developed through a collaboration between Ericsson and Fraunhofer Institute for Integrated Circuits. It is designed to deliver better audio quality than the existing base codec, Sub-band Codec (SBC), which is a part of the Bluetooth specification for any audio device. Although Bluetooth LE Audio devices can support more advanced audio codecs such as AAC, aptX, and LDAC, LC3 is an essential part of the standard.
LC3 offers a qualitative improvement over SBC, even when the bitrate is lowered to half. LC3 can cover a wide range of sounds, ranging from basic audio calls to high-quality music transmission. Manufacturers can prioritize battery life or audio quality based on the product and the intended purpose. Meanwhile, a longer battery life means audio accessories can also have additional sensors for fitness, wellness tracking, or refined audio quality.
Notably, Bluetooth uses the same 2.4GHz spectrum as Wi-Fi, cordless telephones, and devices such as baby monitors, and the congestion in the airwaves can lead to loss of signal. To mitigate losses, the LC3 codec also includes a Packet Loss Concealment (PLC) algorithm that automatically tries to fill up gaps in the audio when a part of the audio signal is lost to effects like interference.
Although Bluetooth SIG has outlined the specifications for LE audio, we have yet to come across major audio manufacturers making devices that support the standard. However, the introduction of native support in Android 13 is likely to expedite adoption by manufacturers building sound equipment such as earbuds and speakers as well as consumer electronics such as smartphones, laptops, AR headsets, smart wearables, etc.
In its 2022 Bluetooth Market Update report, Bluetooth SIG predicted LE audio will drive the adoption of personal audio peripherals such as earbuds and headphones and result in a total shipment of more than 600 million earbuds, which will make up for two-thirds of the total Bluetooth peripherals sold by 2026. In addition, the market for hearing aids is also expected to grow by 260% over the next four years. Lastly, the group recognizes more than 60 million public places worldwide that can be used as Bluetooth broadcast centers with wider adoption of LE audio.
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