Sometimes a chord just needs a bit more bite.
The perfect vowel for this seems to be ‘ah’, which is found in words like Heart (Hah….ert), but shows up most often in English when we’re singing a Long ‘I’, as in:
The extra bite that gives the word, and the chord, more brilliance and more excitement can be added with just a little bit of upper lip snarl – so that some of the front teeth are showing. This is the ‘Ah’ Snarl. My Director cue for it is a claw hand, and a pulled back upper lip display of my teeth. Not pretty – but you do what works.
However, because concrete, physical things don’t work for everyone, I sometimes need to also ask the singers to add just an eyedropperful of Edith Bunker (http://www.youtube.com/watch?v=1F9vRVyV914 ) to the sound – so that what they hear in their own heads is a little edgy.