You would have to switch the creatures voiceset to the appropriate base, and then use the applicable coice chat to do the sound.
// Play a voice chat.
// - nVoiceChatID: VOICE_CHAT_*
// - oTarget
void PlayVoiceChat(int nVoiceChatID, object oTarget=OBJECT_SELF)
Sadly, voiceset changing is only possible with nwnx though, so if you want to swap on the fly to play specific voice chat sounds, you'll have to use that. If you just want a creature to use its particular voice sounds, you'll be fine.
Here's all the voice chat constants available (copy/paste from nwscript.nss):
int VOICE_CHAT_ATTACK = 0;
int VOICE_CHAT_BATTLECRY1 = 1;
int VOICE_CHAT_BATTLECRY2 = 2;
int VOICE_CHAT_BATTLECRY3 = 3;
int VOICE_CHAT_HEALME = 4;
int VOICE_CHAT_HELP = 5;
int VOICE_CHAT_ENEMIES = 6;
int VOICE_CHAT_FLEE = 7;
int VOICE_CHAT_TAUNT = 8;
int VOICE_CHAT_GUARDME = 9;
int VOICE_CHAT_HOLD = 10;
int VOICE_CHAT_GATTACK1 = 11;
int VOICE_CHAT_GATTACK2 = 12;
int VOICE_CHAT_GATTACK3 = 13;
int VOICE_CHAT_PAIN1 = 14;
int VOICE_CHAT_PAIN2 = 15;
int VOICE_CHAT_PAIN3 = 16;
int VOICE_CHAT_NEARDEATH = 17;
int VOICE_CHAT_DEATH = 18;
int VOICE_CHAT_POISONED = 19;
int VOICE_CHAT_SPELLFAILED = 20;
int VOICE_CHAT_WEAPONSUCKS = 21;
int VOICE_CHAT_FOLLOWME = 22;
int VOICE_CHAT_LOOKHERE = 23;
int VOICE_CHAT_GROUP = 24;
int VOICE_CHAT_MOVEOVER = 25;
int VOICE_CHAT_PICKLOCK = 26;
int VOICE_CHAT_SEARCH = 27;
int VOICE_CHAT_HIDE = 28;
int VOICE_CHAT_CANDO = 29;
int VOICE_CHAT_CANTDO = 30;
int VOICE_CHAT_TASKCOMPLETE = 31;
int VOICE_CHAT_ENCUMBERED = 32;
int VOICE_CHAT_SELECTED = 33;
int VOICE_CHAT_HELLO = 34;
int VOICE_CHAT_YES = 35;
int VOICE_CHAT_NO = 36;
int VOICE_CHAT_STOP = 37;
int VOICE_CHAT_REST = 38;
int VOICE_CHAT_BORED = 39;
int VOICE_CHAT_GOODBYE = 40;
int VOICE_CHAT_THANKS = 41;
int VOICE_CHAT_LAUGH = 42;
int VOICE_CHAT_CUSS = 43;
int VOICE_CHAT_CHEER = 44;
int VOICE_CHAT_TALKTOME = 45;
int VOICE_CHAT_GOODIDEA = 46;
int VOICE_CHAT_BADIDEA = 47;
int VOICE_CHAT_THREATEN = 48;
Tiger roars are likely the battlecry ones.
