Need to identify an effect

Hi guys, I didn’t know where to ask that, hope I’m in the right section.

Well, I’m trying to identify an effect, it’s some kind of sustain effect that increases in volume, you can hear it here:

https://youtu.be/tVVYOvEIxy0?t=1m19s

Or here:

https://youtu.be/0gzU8dGFG9s?t=2m54s (and repeating through the song)

Could you help me to identify this effect and possibly a plugin that could make it?

Thanks.

For the piano in the first song: Increase the string resonance level. (In The Grand 3 it’s called sustain resonance; this only works while the sustain pedal is down).

In the second song: Backwards reverb with a long reverb tail.