Help with this Sound effect

Question

what is this sound effect. if you go to youtube and search Nero1x, and go to his 2nd newest video called loading, then go to 0:15 you'll hear a sound effect. Please let me know what this sound effect is called.

Answer 1

It is called a filter sweep. That is specifically a low-pass filter. A low-pass filter significantly reduces the volume of all frequencies above a set frequency (removes all the high sounds). The sweep happens when the filter is automated to lower to that set frequency. The frequency at which the low-pass starts gets lower and lower until you only have bass frequencies.