I think it would make the game a bit more fun if we had more announcer voices(not just the "The overmind is under attack/dying"). For example, something along the lines of Starcraft, where(in that game, at least) if your units are under attack, the announcer will say "Our forces are under attack". Of course we couldn't have this for players getting attacked. It'd be better for just structures that are under attack.
In fact, there's already an announcement when the reactor/overmind is under attack, but it's just text. If it had an announcer say the words, then it would make the game a lot more fun, in my opinion. It would make the game a bit more immersive.
If the structures are being hit by enemies, it only plays seldom, so that it's not constantly spamming the sound.
If a structure is hit, it says "Our base is under attack."
If a player is hit, it says "Our forces are under attack(but not for the player getting hit)"