The sound begins deep, like a gigantic bubble slowly coming to the surface of a swamp, but also sharp and light, like a thin metal blade running over polished marble.

Things get weird at the end of Session 0.

There's a very particular sound that may be heard in the Zone right before things get strange. Veteran hunters know of it and will recommend extreme caution. Rigasia seems to be interested in censoring it.

The party experienced the sound at the end of Session 0 and it was very probably related to the crash of the helicopter carrying Agent Kort to the staging ground. Kort forced both Clark and Gaia to sign non-disclosure agreements about it.

During Session 1, Rose was able to clearly perceive the sound despite her ears being clogged with water.

At the end of Session 1, Iorena Sevel was very scared to learn that the sound had been heard in the outer ring of the Zone and told Gaia to run as far away as possible if she heard it again.

The sound might be related to Floating Water.