AAC-ELD (Enhanced Low Delay AAC) is optimized for low latency real-time communication. AAC-ELD is a superior speech codec that offers full HD voice quality, providing clear, natural communication for FaceTime calls according to Apple. The AAC-ELD is based on AAC but it's only applied to calls for Airpods 3.

Codec details
Fraunhofer IIS
Max Bitrate
96 kbps