When we choose Bluetooth audio products, we often see some technologies or abbreviations like TWS, ANC, ACC, SBC, AptX, etc. on the details page. Each of them represents a unique function, technology or device. So what do they mean?
- Bluetooth audio coding standard
For Bluetooth audio wireless transmission, we usually mention the coding method. Common coding methods include the following:
SBC: (Subband Coding)
This decoding method is the most basic and common decoding method. All Bluetooth audio chips support this protocol.
AAC: (Advanced Audio Coding)
AAC is a common decoding method for iPhones, similar to SBC, but with slightly better sound quality than SBC.
AptX:
AptX is a patent of Qualcomm, which includes aptX, aptX HD, aptX Low Latency, aptX adaptive and aptX Lossless. They are traditional aptX, high-quality aptX, low-time delay aptX, adaptive aptX and lossless aptX.
LDAC:
LDAC is a high-quality audio codec produced by Sony, which is close to lossless decoding. It is the first encoding format to obtain Hi-Res Audio Wireless (wireless high-resolution audio standard) certification. In the audio industry, Hi-Res is commonly known as the "little gold label", and its full name is High Resolution Audio, which is translated into Chinese as high-resolution sound quality.
LHDC: (Low-Latency Hi-Definition Audio Codec, high-quality Bluetooth codec)
It is also close to lossless decoding, promoted by Huawei, comparable to LDAC. It has also passed the Hi-Res Audio Wireless certification.
L2HC: Low Latency High Clarity, low-latency and low-complexity high-definition audio codec)
L2HC is my country's first high-definition wireless audio codec standard. The biggest highlight of L2HC is that it supports a peak bit rate of up to 1920kbps, which is currently the only wireless audio coding standard that exceeds the CD-level lossless sound quality requirements.
LC3: (Low Complexity Communication Codec)
LC3 is a new audio codec introduced in LE Audio. It was introduced as the successor to SBC in the Bluetooth 5.2 update. It can greatly improve the quality and latency of Bluetooth official standard audio coding. It is predicted that LC3 will replace SBC and AAC as the universal Bluetooth audio coding in the future. If we want to choose a Bluetooth product with good sound quality, purely from the perspective of encoding technology, we believe that AptX-HD≈LHDC≈LDAC>AptX>AAC>SBC.
- Wireless audio transmission certification standards
Hi-Res Audio Wireless small gold label: (High-Resolution Audio, high-resolution audio standard)
Hi-Res Audio Wireless is a wireless high-quality music transmission and playback standard launched by the Japan Audio Association (JAS) in 2018. In 2020, a new version of the Hi-Res Audio Wireless standard was launched for the TWS headphones that have been very popular in recent years.
HWA: (Hi-Res Wireless Audio, high-definition wireless audio standard)
HWA is a high-definition wireless audio certification standard initiated by the China Electronic Audio Industry Association, China Electronics Technology Standardization Institute and Huawei, and first released by China.
What is the relationship between Hi-Res Audio Wireless, HWA and LDAC, L2HC, and LHDC?
It can be considered that Hi-Res Audio Wireless and HWA are certification standards, while LDAC, L2HC, LHDC and AptX are encoding standards. The certification standard stipulates a delay, sampling rate and bit rate standard. The encoding method is responsible for achieving this standard.
Currently, LDAC and LHDC are the encoding standards for Hi-Res Audio Wireless certification.
Currently, the optional Bluetooth encodings given in the HWA official website include L2HC, LC3, LHDC, LDAC, and aptX Adaptive.
If we want to choose a product with good Bluetooth sound quality, of course the first choice is a product that has obtained both Hi-Res Audio Wireless and HWA dual certifications.
- Bluetooth audio function protocol
For Bluetooth audio functions, we often see many protocols and technologies. Here we briefly list some common ones:
HSP (Head-Set-Profile)
As the name suggests, it is the most commonly used configuration protocol to connect our Bluetooth headsets and mobile phones. It mainly focuses on realizing headset functions and realizing audio transmission and control;
HFP (Hands-Free-Profile)
HFP adds more extended control functions on the basis of the HSP protocol, and is often used in scenarios where hands-free devices control mobile phones;
A2DP (Advanced Audio Distribution Profile)
A2DP is used to transmit high-quality sound between multiple audio devices and supports the transmission of stereo audio signals.
AVRCP (Audio/Video-Remote-Control-Profile)
Used to send commands (such as some forward, pause and play instructions) from the control device (or stereo headphones, etc.) to the target device (such as a computer with MediaPlayer, etc.), often used in conjunction with the A2DP protocol.
TWS: (True Wireless Stereo)
The mobile phone connects to the main headset, and then the main headset quickly connects to the secondary headset wirelessly, which can truly realize the wireless separation of the left and right channels of Bluetooth.
ANC: (Active Noise Cancellation)
Use the algorithm to generate sound waves opposite to the noise to cancel the noise, which is suitable for scenes that shield environmental noise;
ENC: (Environmental Noise Cancellation, environmental noise reduction),
Use signal processing algorithms to analyze and filter noise, which is suitable for scenes that improve the clarity of call voice.
EQ (Equalizier)
It can adjust the output size of different frequency bands of music signals, which can be understood as sound effect adjustment.
- So how to choose a suitable Bluetooth audio device?
The first step is to determine the Bluetooth codec supported by your phone.
If you buy headphones that support aptX-HD and LDAC codecs, but your phone does not support aptX-HD and LDAC codecs, you will not be able to use the sound quality of the headphones. Therefore, you should first understand whether your phone supports the relevant codecs.
Secondly, look at the codecs supported by the Bluetooth device.
Although L2HC, aptX-HD, LDAC, and LHDC are relatively excellent, aptX-HD and LDAC are more mainstream codecs. Many devices can support both codes (or one of them), while LHDC and L2HC are relatively unpopular. Therefore, it is recommended to choose a Bluetooth receiving device that supports aptX-HD and LDAC codecs.
At the same time, check whether there is a small gold label or HWA certification. Of course, it is best to obtain dual certification.