If it doesn’t sound quite right, you can try adjusting the length slightly or picking a different fraction of the sound effect to use. Then, just sync up the voice beeps as you normally would. You might want to start with a third of a second and adjust it from there. Then you will want to trim the sound effect to way less than a second. Maybe you’ll want a bell sound effect for a character with a high, musical voice, or a chainsaw sound effect for a low robotic voice. Alphys were supposed to suggest a high, nasally voice. Undyne’s voice beeps were chosen to make her voice sound lower, maybe even a little hoarse. Obviously, you’ll want the sound effect to suggest what the character’s voice would sound like. Essentially, though, you find a sound effect (you can find a huge library of free ones HERE, or for more more 8-bit appropriate ones, there are some free sound effects HERE or HERE just to start you off, or you can make them in a tracker like Sunvox or in a normal audio program using a chiptune soundfont, or use sound effects straight from Undertale). I’m not very skilled at this, and it shows. I did answer this once, but deleted my tutorial, because it was…frankly unhelpful and embarrassing.
