Lilo's idea for an alien invasion alarm to improve the hula school is rejected, so she tries to write a letter to the mayor about it. Meanwhile, a loud, sonic-blasting experiment causes Stitch to temporarily lose his hearing, so earless Pleakley is given the job of capturing Yaarp himself. While Pleakley is off looking for Yaarp, Gantu captures Stitch and will not let him free without a trade.
- Moral: Even small people can have big voices.
- This episode emphasizes the humans' blindness to the aliens, as no one (except for Nani, David and Cobra) believes Lilo about the aliens, even though they are in plain sight.
- It is unknown why Pleakley tried to suck up Yaarp with a vacuum, as he would never fit through it.
- Yaarp is one of the few known experiments named by someone other than Lilo.
- He is also one of the few known experiments to be rehabilitated by someone other than Lilo and Stitch.
- Yaarp was named after a word from Pleakley's home planet.
- Yaarp is capable of controlling the intensity of his sonic blasts, depending on how he feels around others.
- Gantu mispronounces the word "aloha" when he attempts to make off with Yaarp.
- Hämsterviel and Reuben do not appear in this episode.