In an effort to be understood, many singers fall into the trap of overemphasizing consonants. While the intent—clear communication—is correct, over-articulation is often a "band-aid" for deeper vocal faults. True diction isn't forced; it is a byproduct of a free-functioning vocal instrument.
If the vocal muscles are not developed and coordinated correctly, diction will remain poor no matter how hard you try to enunciate. Good diction is made possible by the Foundations of Singing: Respiration, Registration, and Resonance. When your vocal muscles (the "stretchers" and "closers") are balanced and your vowels are properly shaped, the articulators are finally set free to move with precision.
Trying to "force" clarity through heavy spitting of consonants can actually cause significant vocal problems:
While heavy consonants hinder us, light and quick consonants can actually help re-educate our muscles. In vocal exercises, consonants act as specific triggers:
Think of your consonants as lightly reflecting off the top of the vowel, rather than pushing the vowel up from beneath. If you find yourself falling behind the beat in a fast exercise, you are likely too heavy. By lightening the volume and increasing the speed of the consonant, you give the vocal cords space to attain the proper size and weight for the pitch.
Articulation should be a "getting out of the way" to allow for greater freedom. As your registration and resonance adjustments improve, you will notice that your diction improves automatically. You won't have to work so hard to be understood; your voice will naturally carry the text with clarity, ease, and deep emotional connection.