I am world building/culture building for a story that I'm writing and one of the races/sapient species is patterned after spiders. I'm willing to take a lot of liberties with the physiology (for example, structurally they resemble Trogloraptors and they have the size range of Shetland ponies), but I would like to base most of what I come up with on actual science.
My question is: how would spiders that size and that intelligent communicate, not just with each other, but with other sentient peoples? Most of what I've found so far (via Google) says that spiders can't hold their breath because of the way they breathe, and so wouldn't be able to speak. I've also read about spiders hissing (not sure if that's on purpose, though) and tapping (that does seem to be intentional).
At this point I'm thinking this race would use a lot of sign/body language to communicate, but I am still hoping for some sort of sounds to add as well.