Bluetooth technology, which allows wireless transmission of audio from devices like smartphones to headphones or earbuds, relies on audio codecs to compress and decompress sound signals. Unlike analog connections, which transmit the entire audio signal without compression, Bluetooth codecs reduce the data size to make transmission more efficient. The most common default codec is SBC, which is universally supported across smartphones, PCs, and audio devices. However, SBC is known for significant compression, which can affect sound quality. A codec is a system that encodes and decodes audio data. For a codec to work, both the sending device (like a phone) and the receiving device (like headphones) must support the same codec. For example, LDAC, a high-quality codec that can transmit up to 990 kbps of data, is only useful if both the phone and the headphones support it. While Android phones generally support a range of codecs, many affordable earbuds and headphones only support SBC and AAC, which are more common but offer lower sound quality compared to newer codecs. The quality of a Bluetooth codec can be judged by factors like bitrate, latency, and the amount of compression. Bitrate, measured in kilobits per second (kbps), reflects the data transfer speed. Higher bitrates usually mean better sound quality, but only up to a point—after that, the improvement becomes negligible. Latency, or the delay between audio being played and heard, is important for real-time applications like gaming. Some codecs, like aptX Low Latency, aim to reduce this delay, but support is limited. All Bluetooth codecs compress audio, which can result in a loss of quality compared to wired connections. Several advanced codecs offer better performance. SBC, the standard Bluetooth codec, has a variable bitrate between 127 and 345 kbps and introduces noticeable latency. AAC, favored by Apple devices, has a maximum bitrate of 250 kbps. LC3, a newer codec integrated into Bluetooth LE Audio, promises better sound quality at similar bitrates to SBC, with lower latency and higher audio depth. aptX, one of the oldest and most popular codecs, supports up to 384 kbps and lower latency than SBC. Its high-end variant, aptX HD, offers 576 kbps and is backward compatible. aptX Adaptive adjusts the bitrate based on the connection’s stability, offering improved flexibility. LDAC, developed by Sony, supports up to 990 kbps and is available on high-end Android phones and headphones. However, it doesn’t significantly reduce latency. LHDC 4.0, developed by the HWA Alliance and used by Chinese manufacturers like Huawei and Xiaomi, supports similar high bitrates and offers Hi-Res Audio certification. Samsung’s proprietary SSC Hi-Fi codec promises 24-bit depth and a 48 kHz sampling rate, but it is only available on Samsung devices. Each codec has its own trade-offs, and the best choice depends on the specific devices being used and the user’s priorities, whether they value sound quality, latency, or compatibility.