- And got the T-shirt
You can line the inside of the cage with plexiglass at the area where they chew. I'd be willing to bet that's at the side closest to the kitchen where they can hear/smell you fixing the veggies. And figure out a way to clamp the ramp down, or put something under it that will muffle the sound.
Also, your pigs will never come to trust you if you keep "flicking" them on the nose. You can't punish a guinea pig. They don't have the capacity to understand.