Kelly Bailey's sound design

[Sinjin]

Hi everyone, this is my first post and I'm pretty new to creating music. I don't have any analog synths or anything. I do know some fundamentals of sound design, and basic additive, subtractive, wavetable synthesis.

I'm working on a Half Life Alyx mod writing the music for it, and I wanted to try and emulate the mood Kelly Bailey managed to create with his original HL2 soundtrack. I'm fascinated by these "watery" kind of sounds he uses in this song especially: https://www.youtube.com/watch?v=Qstnizb2Y0o the sound is prominent and easy to hear in the very beginning of the song.
I know that there's some kind of filter sweep and obviously a delay used but I can't manage to quite recreate it.

Any advice would be appreciated, even if you can just point me in the right direction in general.

Thanks!

[MOF]

The main effect is a vocoder then added delays/reverb.

[BJG145]

...yes, I think you're right. I started messing around earlier with a synth flute and progressively adding on distortion, resonant filter and echo while tweaking the settings...

https://soundcloud.com/qchord/fluteonly/s-njhdheMYqUm

...and it's likely got a whole bunch of this kind of FX mangling on it, but starting with a vocoder sound.

https://soundcloud.com/qchord/voc/s-aS9xE4vkoPf