After my post on designing languages I had comments (here and on the Analog forum) from three people, which I thought I'd follow up on tonight.
Bill Gleason asked about translators.
A universal translator like the one in Star Trek is effectively a deus ex machina, an intervention on the part of the designer to allow us to bypass the real problems of different languages.
A mechanical translator can do a lot when it comes to predictable language structures - finding word boundaries by identifying repeating sets of sounds, tracking the structure and the sequence of those words. A really snazzy neural-network-style translator would probably also be able to do a good job of tracking phrases that repeat, and be able to do fuzzy categorization of words so it could capture exceptions to rules and things like that. It would also be able to do meaning to a certain extent, but I'm not sure how it would push past literal meaning to social meaning, for example. I suppose it would have to depend on how high you assumed the technology was.
I think it would be really interesting to have a translator machine that was really helpful but also limited in predictable ways. One issue a really "universal" translator would have to address would be how to incorporate information from the surrounding visual and social context - and that would be very tricky. Certainly it would require a device that could follow things like eye gaze and body position.
Bill also asked about body language. I talked about that yesterday so I won't go too deep, but if you assume that two groups of aliens are each able to identify discrete objects in their environment, then I think there would be a high likelihood that pointing would be used by both. Beyond that, a human trying to interpret alien gestures would need to be very sensitive to surrounding context and remember not to make assumptions about natural meaning for a given gesture. A shoulder-lift might not mean the same as a shrug, or possibly the alien might use an eye-gaze gesture similar to ours, but that is not accompanied by a shoulder motion. I don't think it's too far out to have two alien groups reach a basic level of mutual comprehension, but watch out for places where categories of objects are defined differently.
Tom Ligon brought up two very interesting ideas: a language based on bioluminescence, and a sound-based language with such vast range that human sounds seem undifferentiated.
Fireflies communicate by bioluminescence, but in a very simple way ("Where are you?" "Here I am!"). For a species with such a language to be able to grasp that humans are communicating, they would have to have an awareness of sound and its potential for carrying messages. They might even have unique alternate means to communicate via sound, as humans have used Morse code on Aldiss lamps, or semaphore (with flags).
As far as the language with vast range is concerned, that's a very interesting one. Human babies must gradually learn what not to pay attention to in their environment, so as to make communication easier without distraction, and so I think this is a completely solid concept. A human would have a tough time with this initially - it makes me think of H. Beam Piper's Fuzzies, who spoke with supersonic pitch. But given a good receiver, a lot of analytical work, and an appropriate sound generator, they might do a good job of speaking the range-language. Among range-language speakers, I think it would be a question of special individuals being able to grasp human language sound concepts. I've met many people who aren't able to hear sound distinctions that differ from their own native language - but on the opposite side, there are always exceptional individuals who are able to hear more subtle sound distinctions.
Greg Ellis peppered me with examples - what an exciting range of species! Look for them in his FOTS universe. The first place I'd start, given a large number of groups like this, would be sound design based on physiology, and believe it or not, the minute you name a group, you've already started language design. I'm going to comment a little on each group he gave me (except two he called the Swarm and the Machines), and I hope this will give a sense of how I get started when thinking through alien languages.
It might be good to ask whether dinosaur-like aliens have flexible lips, for example, because inflexible lips might restrict their ability to create consonants like p/b/w/m, or vowels like o/u. It looks already as though the Dwa'Kim have such flexibility - that could be used as a distinction between the two languages.
My question about caterpillar aliens is whether they have a hard palate, and whether they have a nose. Both are useful to have, the palate being good for consonants like j (assuming it's pronounced "dzh") and the nose for sounds like n. The species might well have a different way of re-routing the air stream to produce a different resonance, the way we do with our noses. The name of the species as given here would actually be possible to pronounce without a palate if the j were pronounced like a y, and the q low down in the throat. But generally speaking the transcription of sounds would have to be considered approximate.
A doglike group. I've got the vibe. It looks like these guys are going to have some really cool growl-like consonants, or multiple qualities of "r." Does the apostrophe mean a glottal stop, a plosive consonant, or some kind of dropped sound? These are possibilities that might help the language expand.
A more humanoid group, and their name is short, so lots of directions to go with this. I'd be looking to culture and social situations of language use to find out more about how the language is used.
Kon'ta Py'ron, Q'Tez, Grymphon
I'm grouping these together because they are relatively insectoid, with hard body parts, which suggests to me that they'll have a lot of means for clicking, creating hums and vibrations, and potentially whistling, all of which are difficult to use English letters for. But for clicks you can always turn to k/p/t/! , and for hums or whizzes you can go for s/z/f (or ph!) Whistles might give you vowels. I wonder a little about "n" and "g" for these groups, but this is all about getting creative - these might indicate sounds created by a combination of hum and click. Think through the type of mandible structure they might have, and whether they would have rubbing surfaces on their legs or other types of sound-producers they could use for language.
And that's it for my thoughts! Thanks for sending me the questions, guys - and I hope these examples have been thought-provoking for other people facing similar challenges.