This from Stephen Zopfi, Conductor and Director of Portland Symphonic Choir, September 23, 2009, while preparing to sing Brahm's "Ein Deutches Requiem"

Let us take as a given that pronunciation for singing is different than pronunciation for speech. (Hence, specialized diction classes for singing)

Let us also take as given that what works for solo singing doesn't always work for choral situations (Hence, we adjust choral pronunciation to find what works for a particular choir in a particular musical situation)

Add to that pronunciation can be modified depending on where a particular note sits in the voice, what sequence of vowels and consonants come before and after, where it occurs in the musical line, and even what musical effect is needed.

Then mix in the fact that no two native speakers of most languages agree on the pronunciation of anything.

Then stir.

Well, you can see that it is a difficult situation. IPA symbols can be tremendously helpful but even with IPA, there is a limit to what they can offer. Like musical notation, IPA can point you in the right direction but no notational system can ever capture the nuance and endless gradations of speech.

Therefore, we do the best we can. We establish a standard and train the best we can. We do our best to listen and to adjust. We practice. For those of you who have had singers diction, have sung the work many times before, or who are native speakers - hang in there. We have a new choir with new adjustments, new standards, new interpretation, new things to listen for, to discover.

In choral singing, performing "as one" is more important than performing "right". Ideally, we can achieve both, but art is in the details.