At present, with an increasing number of audio products using Bluetooth for communication, Bluetooth SIG has launched a new generation of Bluetooth audio technology - LE Audio, so as to minimize the power consumption of Bluetooth audio transmissions and offer more audio capabilities. The features and related applications of Bluetooth LE Audio technology are introduced here.
LE Audio with better sound quality, lower power consumption, and more innovative functions
Bluetooth technology has been widely used in smart phones and various audio devices, such as Bluetooth speakers and Bluetooth headsets. However, classic Bluetooth technology still has its disadvantages in terms of audio transmission, such as sound quality and power consumption, which need to be improved.
In view of this, on the basis of 20 years of Bluetooth technology development and innovation, Bluetooth SIG has made constant efforts to improve the performance of Bluetooth Audio technology, and in the first half of 2020, launched the Bluetooth Low Energy audio (LE Audio) specification. Compared with the Classic Audio specification, LE Audio can provide better sound quality and lower power consumption, and adds in functions such as multi-streaming, hearing aids, broadcast (audio sharing), etc. These innovative new use cases of Bluetooth applications will once again change the way we experience audio and further connect us to the world around us.
As the name suggests, Classic Audio runs on Bluetooth Classic radio, while LE Audio runs on Bluetooth Low Energy radio. LE Audio not only supports the development of the same audio products and use cases as Classic Audio, but also introduces thrilling new features that are expected to improve performance and create new products and use cases.
In Bluetooth 5.2 specification, Bluetooth LE Audio is the most important technical innovation bringing revolutionary changes to the application of Bluetooth Audio. At present, wireless headset is the most common application of Bluetooth Audio, but Bluetooth headset faces audio delay, short running time and other problems, which can be effectively solved by using LE Audio. LE Audio includes a new high-quality and low-power audio codec, namely the Low Complexity Communications Codec (LC3). Although LC3, a brand new codec, is still not as good as APTX and APTX-HD Audio codec, it offers greater improvements in encoding efficiency and quality compared with the classical Bluetooth Audio codec SBC Even at low data rates, LC3 can provide high quality, which will provide developers with great flexibility and enable them to make better design tradeoffs among key product attributes, such as audio quality and power consumption.
In general, maintaining high audio quality at a low bit rate is a hard nut to crack. However, LE Audio can provide better audio quality at a low bit rate. A large number of listening tests show that even if the bit rate is decreased by 50%, LC3 can still offer higher audio quality than the SBC codec provided with Classic Audio. With LE Audio, developers can balance audio quality and power consumption at their own discretion, with sampling rates of 8, 16, 24, 32, 44.1 and 48kHz, bit rates between 16 and 320kbps, and optional frame rates of 7.5 and 10ms, enabling developers to use this power saving function to produce products that can extend the battery life, or on the condition that the current battery life is sufficient, reduce the overall size by using a smaller battery.
In addition, with Multi-Stream Audio, multiple and independent audio streaming transmission can be synchronously carried out between the single audio source device (such as smart phones) and a single or multiple sink devices. This allows developers to use multi-stream audio capabilities to improve the performance of products such as real wireless earbuds. For example, it can provide a better stereo listening experience, improve the seamless use of voice assistant services, and make switching between multiple audio source devices smoother.
LE Audio changes the way of wireless headphones designs
The new Bluetooth 5.2 standard supports one-master multi-slave audio streaming applications based on connection, and its algorithmic mechanism ensures that multiple sink devices receive master device data synchronously. Its protocol stipulates that every frame of data sent by Bluetooth transmitter will have a time limit, so as to discard the data received from the slave device after the time window. This means that the sink device only receives data within the effective time window, guaranteeing the synchronization of data received from multiple slave devices.
The Multi-Stream Audio feature of LE Audio will give all users of real wireless headsets a binaural transmission experience. Smartphones can transmit the same audio signal to both ears at the same time, unlike Apple's "TWS" technology, which sends audio signals to one headset and forwards them to the other. Using the Bluetooth audio products based on LE Audio, audio signals can be transmitted to both headsets simultaneously to develop the real wireless headsets. In this way, the Multi-Stream Audio capabilities will improve the connective stability of Bluetooth headsets, reduce latency, and increase the smoothness of switching between different audio devices.
Hearing aids are another innovative feature integrated into LE Audio. LE Audio adds support for hearing aids based on its low power consumption, high quality, and multi-streaming capabilities. Bluetooth Audio has brought huge benefits to most of the world's population, such as wireless calling, listening and watching, enhancing safer, productive, and entertained. LE Audio will drive the development of Bluetooth hearing aids so that more and more people with hearing loss can enjoy all the benefits of Bluetooth Audio, and within a few years, it will make most of the new phones and TVs more accessible to users with hearing loss.
The broadcast audio function is also incorporated into LE Audio, allowing the audio source device to broadcast one or more audio streams to an unlimited number of audio sink devices. Broadcast audio offers important new opportunities for innovation, including enabling the new Bluetooth case of "audio sharing".
Bluetooth audio sharing can be personal or location-based. Personal audio sharing enables people to share Bluetooth audio experiences with others around them, for example, sharing music in smartphones with family and friends. Location-based audio sharing enables the sharing of Bluetooth audio in public places such as airports, bars, gyms, cinemas and conference centers, or the provision of audio in multiple languages, so as to enhance the visitors' experience.
It can be seen from the Bluetooth 5.2 specification that LE Audio is an update at the level of pure software protocol stack, which is different from CODER PHY and LE 2M PHY of Bluetooth 5.1 that requires hardware support; that is, for many manufacturers' products, LE Audio function of Bluetooth 5.2 can be supported by directly updating the software development kit (SDK).