audioOS 9.9.18.4 (build 22L255) is an official Apple over-the-air update for the HomePod (2nd generation), released on 2025-03-31T17:29:46Z. The update package is 1.47 GB. This is a delta (partial) update that requires 16.3.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: ec910b5047759bbee49da29756854149a9fca88d5b2036b97e8f30628d0896b1.aea.