Well generally higher voices tend to be associated with youth/goodness and lower with age/and ambiguity if not evil. Of course there are exceptions and extremely high vocal ranges may have supernatural associations (eg Queen of the Night, Oberon). However please note that these associations should not be related to the game .... you cannot assume that the bass-baritones will be wolves and a lyric soprano the seer. You will not be required to sing exactly it is just to give me the chance to have fun with my narrations - and you can all camp it up like the prima donnas / primo uomos that you are
Also sorry to be a pain in the proverbial but I have slightly altered the concept for the scenario from an opera festival to an operatic competition a la Cardiff Singer of the World so to add to amusement and give a ME connection please also let me know which Middle Earth race you wish to be and preffered region to represent. Also your operatic name (thanks Gwathy I knew there was a reason I asked for names originally despite the fact that unlike a paper notice board the writer is obvious.
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As ME's senior principality, Belfalas will be the host for the "Dol Amroth singer of Middle Earth" competition which will start as soon as there are a decent number of participants.