I've been having an interesting discussion with some of my students about diction in singing. There is a great deal to discuss when it comes to this question! There are various points of view about diction for classical as opposed to "pop" singers, as well as recording versus performing live. I'm not sure I agree with some of the prevailing wisdom out there about this either. For instance, I have heard opera singers sing vowels, pop singers sing the consonants." Pish. All singers must sing the vowels first and foremost! Yes even pop singers. Why? You can't sustain a consonant (ok you could sustain a voiced consonant technically, like the sound zzzzzzz)! We sing ON the vowel. For singers, obviously the vowel is where sound is actually produced. Duh you say.
Now what about WORDS? Yes yes yes!!!! What could be more important for a singer? We are the poets of the music world. We speak the sentiments that the songwriter wants to say...maybe we are the songwriter. Even more connection to the text in that case, but it shouldn't matter. Unless the singer is scatting or using sounds in a purely playful way (ala Bobby Mcferrin for instance) he/she is obligated to make herself understood. But how?
The tension that exists in the singer between singing on the vowel and making the words clearly understood is resolved by singing the consonants clearly but in a relaxed way. Overarticulation is not the answer. Often times in fact, when singers try to hard to use "good diction" they end up sounding just bad and the words aren't necessarily any clearer anyway. Befriend your consonants. Don't beat them to death with your tongue for God's sake. Clarity does not mean tension in the tongue lips or jaw. (OH NOOOOOOoooooooo!) Be thou nice to thine singing parts, and in turn, they wilt oblige you in singing with beauty and clarity.