audioOS 9.9.18.4 (build 22L255) is an official Apple over-the-air update for the HomePod (2nd generation), released on 2025-03-31T17:29:47Z. The update package is 1.47 GB. This is a delta (partial) update that requires 16.5 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 3fe328330fab7f1097b47343227ea90151e1bcb658666ad32018b2ef2ec07611.aea.