AAC
Advanced Audio Coding — Apple's preferred Bluetooth codec.
AAC over Bluetooth carries lossy audio at 256 kbps. Apple optimized AirPods around AAC, so AirPods + iPhone delivers consistent latency and quality. On Android the AAC encoder quality varies by manufacturer — same codec, different sound. AAC sits between SBC (universal floor) and aptX/LDAC (higher bitrate alternatives) in audio quality.