I think all the above snipped points are well made.

: Did they speak? They must have been able to. As Morgoth's chief lieutenants and commanders of his army, they must have
: been capable of giving orders to the Orcs and other creatures. No Balrog is recorded as saying anything in The Simarillion, but then the story doesn't ever get 'close' to the them - certainly not as close as it does to the Nazgūl in The Lord of the Rings.

: The Book of Lost Tales (which, while hardly canonical, does give some guide to Tolkien's thinking) does record Balrogs speaking. For example, ... Gothmog lord of the Balrogs, captain of the hosts of Melko, took counsel and gathered all his things of iron that could coil themselve around and above all the obstacles before them. These he bade pile themselves before the northern gate ... (HoMe 2:176). Similarly, Gothmog yelled when he was attacked by Ecthelion (HoMe 2:184).

: The Balrog in Moria never says anything, probably because it did not speak Westron. It seems to have slept from the end of the First Age until awakened by the Dwarves around TA 1980, after that it does not appear to have ever ventured outside Moria. Thus it had no need or opportunity to learn Westron - a knowledge of Orkish tongues would have sufficed.

Orcs spoke Westron too.

: It is worth noting that Shelob does not say anything either, although she must have been able to speak. Her mother Ungoliant could, and so could her daughters in Mirkwood - so she must have been able to. Perhaps she also did not speak Westron - like the Balrog, she would have had little need or opportunity to learn it.

I don't think that's it. Gandalf spoke to the Balrog in Westron and Gandalf seemed to presume the Balrog could understand him. The Balrog was a maia of some power after all. After Gandalf's challenge its stated that "The Balrog made no answer". Not that it couldn't answer, I think the implication is that it chose not to answer. It just attacked.

Russ