The 30dB in ANC marketing is an average below 1kHz. Apply 20dB of attenuation to a 90dB subway car and 70dB remains, feeling about a quarter as loud — here is attenuation converted into perceived loudness, and where passive isolation takes over.
LDAC's 990kbps is 70% of a CD's data rate; AAC's 256kbps is 18%. But iPhones stop at AAC, and LDAC drops to 330kbps when conditions are poor. Here is every codec converted against the source.
Bluetooth 5.4's new features — PAwR and Encrypted Advertising Data — were built for electronic shelf labels, not audio. What actually changes sound is LE Audio and the LC3 codec. Here is the real 5.3 vs 5.4 difference, straight from the official spec documents.
Codec specs come up often when choosing wireless earphones, but how those differences play out in real listening environments is rarely well explained. Here is a clear, spec-based breakdown of how LDAC, aptX, and AAC diverge on bitrate, latency, and device compatibility.