LE Audio
LE Audio is a next-generation Bluetooth audio standard, first announced in 2020 and finalized in July 2022. It has been described by the Bluetooth SIG as “the largest specification development project in the history of the Bluetooth SIG.” It is developed based on Bluetooth Low Energy (Bluetooth LE) technology, but is specifically designed for audio transmission, not just short-term data transfer. LE Audio operates on Bluetooth Low Energy radio, making it more energy-efficient than standard Bluetooth and helping to extend device battery life.
LE Audio aims to significantly enhance the wireless audio experience by offering several key advantages and new features:
• Improve audio quality and efficiency :
A new Low Complexity Communication Codec (LC3) has been introduced . LC3 offers superior audio quality compared to Bluetooth Classic’s SBC codec, while also providing the power-saving features of Bluetooth Low Energy. The Bluetooth SIG claims that LC3 delivers better audio quality than Bluetooth Classic even at lower bit rates, thus significantly reducing bandwidth usage. It can provide higher audio quality at the same data rate, or still deliver the same or better audio quality as SBC at a 50% reduction in bit rate (and power consumption). This provides product developers with tremendous flexibility in balancing audio quality and power consumption.
• Lower power consumption :
Operating on Bluetooth Low Energy radio helps extend the battery life of devices such as smartphones, tablets, wireless headphones, and Bluetooth speakers.
• Lower latency :
The Bluetooth SIG claims a latency of 20-30 milliseconds, which is particularly beneficial for gamers and can also reduce audio-visual desynchronization issues when using wireless headphones to watch TV or movies.
• Multi-Stream Audio :
This new feature enables audio source devices (such as mobile phones) to transmit multiple independent and synchronized audio streams between one or more audio receiver devices.
It can improve the performance of true wireless earbuds, such as providing a better stereo experience, enabling seamless use of voice control services, and smoother switching between multiple audio source devices.
Unlike previous models where only one earbud connects to the phone and then forwards the connection to another, multi-streaming allows both earbuds to connect wirelessly to the phone directly, providing a more reliable connection and reducing latency or synchronization issues.
It also allows a device to connect to multiple headphones and can be selected to connect only a single headphone.
• Broadcast Audio / Auracast ™
This is a brand new feature that allows a single audio source device to broadcast one or more audio streams to an unlimited number of Bluetooth audio receivers.
Audio broadcasts can be open (any device within range can join) or closed (requires the correct password to join).
This opens up new applications for audio sharing , which can be personal sharing (such as sharing mobile music with family and friends) or location-based sharing (such as sharing TV audio in public places such as airports, gyms, and cinemas, or theaters providing multilingual audio and assisting people with hearing impairments).
• Improved hearing aid support :
◦ LE Audio has significantly increased the integration of Bluetooth technology into hearing aids, which is expected to bring longer battery life, smaller and more discreet hearing aids, and allow hearing device users to receive audio directly from audio sources such as TVs and smartphones.
• Other advantages :
◦ Through “Periodic Advertising Enhancement”, LE Audio can provide better sound quality at long distances.
◦ LE Audio has no licensing fees, unlike other competitors such as aptX that require paid licensing. Due to lower costs, its supported devices may have lower prices.
It allows single-mode Bluetooth Low Energy radios to simultaneously support wireless data transmission and audio streaming.
◦ The new audio profiles are designed to be more flexible and adaptable to both new and existing use cases.
To support LE Audio, devices must have Bluetooth 5.2 or 5.3 hardware and integrate the isochronous adaptation layer (ISOAL) option added in Bluetooth Core Specification version 5.2. This allows Bluetooth LE devices to support streaming audio. It’s important to note that both the audio source device (such as a phone or tablet) and the receiver device (such as wireless headphones or speakers) must support LE Audio to achieve their full potential. However, since manufacturers can develop products that support both Bluetooth Classic Audio and LE Audio, many LE Audio devices are expected to continue supporting Bluetooth Classic Audio to ensure backward compatibility. LE Audio does not mandate that devices support Bluetooth Classic Audio.
LC3
LC3 (Low Complexity Communication Codec) is a brand-new audio codec introduced by LE Audio, designed to provide high sound quality and low power consumption .
The following are the features of the LC3 in terms of audio quality:
• Superior sound quality compared to SBC :
◦ The LC3 is designed to deliver higher audio quality than the Bluetooth Classic SBC codec at the same data rate .
The Bluetooth SIG points out that LC3 outperforms SBC in audio quality even at lower bit rates . For example, SBC compresses a 1.5 Mbps audio stream to 345 Kbps, while LC3 delivers better perceived audio quality at a lower bit rate of 160 Kbps.
◦ Through the Bluetooth SIG audio codec demonstration, users can actually compare the differences between the two codecs.
• Flexibility that balances sound quality and efficiency :
The biggest advantage of the LC3 lies in its “high sound quality and low power consumption” characteristics. This provides product developers with great flexibility, allowing them to balance key product attributes such as sound quality and battery life.
Specifically, LC3 can provide higher sound quality at the same bit rate and power consumption, or provide the same or better sound quality as SBC with a 50% reduction in bit rate (and power consumption).
This means that developers can choose to: provide higher sound quality than current products while maintaining the same battery life; or extend battery life to twice the length while maintaining the same sound quality ; or even extend battery life by 50% while improving sound quality.
• Results of the audio perception test :
Based on subjective listening tests (where real people listen to and score different audio samples), the LC3’s sound quality was considered virtually indistinguishable from the reference signal . In one report, the LC3 scored 4.8 out of 5, while the reference signal scored 4.82 out of 5, indicating that its sound quality is extremely close to the original reference audio.
• Technical Specifications :
◦ The LC3 supports sampling rates from 8 kHz to 48 kHz, and the data rate per channel can be set between 16 and 320 Kbps for optimal sound quality.
• Developer options :
While all LE Audio products must support LC3, the Bluetooth specification also allows for the addition of other codecs or the use of custom codecs. LC3 may also become an optional codec for Bluetooth Classic in the future.