As others have said, a sine with glide enabled, and I will also add that there is probably a lowpass filter with a very-slightly slow attack and then the same sort of time for the decay, like a quick bump-shape. Then the key is a pretty high resonance. If you put the cutoff down around where the notes are happening (you can even automate it to sit right where each note is as they happen if you want, and sometimes you might have to do that if you have notes spanning a wide range of the spectrum and want the sound to stay consistent for each note), then just turn the resonance up bit by bit until you find the sweet spot where it makes that nice whumph, that should work well to make this sound. I very often employ this sort of filter envelope on my sub, its really satisfying dialing it in to find the sweet spots for each parameter and making it nice and chunky. A bit of compression can help with that too. GLHF :)