Even though the film was entirely produced by Hanna-Barbera, with the exception of "Castle Thunder" being heard a few times, none of Hanna-Barbera's famous sound effects show up in this film. This became more common with the company during the 1990s. See more
[Pip's a gargoyle and trying to speak
It's gargoyle language, he can only speak when the rain comes out of his mouth, or the wind blows over his teeth.