The embedded "song" features a c major scale for each of the three patches, each of which is its own track in the provided logic file. A brief overview of each description follows:

Percussive:

Dropping the Filter and Amp Envs immediately after the sound results in a plucked sound - this is sort of akin to pizzicato rather than percussive, but then, pizzicato sounds are percussive when you consider the clipped nature of the sound.

Pretty:

I turned the transpose up to pitch each sound higher then gave each one semitones back at the original pitch (much softer). This makes the sound higher pitched, which is instrumental in "pretty sounds".

Alien:

Similarly as above, I added semitones at the original pitch. I fiddled with the low pass, increasing the resonance to add the higher "alien" sounds. I also dragged out the sound of each note so that they last longer after the key is released, so that the middle of the scale still has residual sound from previous notes.

Comments: I commented on one patch per classmate:

Percussive: Dan Cheng

Pretty: Naomi Silverstein

Alien: Mauricio Cano