This is what their voices sound like! By the way, NN's name was presumably "eñe" prior to being replaced by Ñ. Also, click "see inside" to hear J's full audio.
Credit 2 Every1, especially @AlfabetonsOfficial (blocked) for the bases of CH, H, N, Ñ, Q's face, RR, S (although I edited it), and U, @LogoFan2016 for the base of K, @PhonicLover44 for the sprites, and Mike Salcedo for Alphabet Lore.