I am a musician and college music professor. At the parish at which I attend church, our priest is Nigerian and speaks with a heavy accent, to the point where his English is sometimes unintelligible. This is frustrating for parishioners, as they cannot understand parts of his sermons.
I have offered to help him with his pronunciation of certain English sounds. He has agreed to accept my help.
I have no formal experience with linguistics; however, I grew up in a bi-lingual (German/English) family, and am gifted with communicating with and therefore helping international students. I taught Ear Training for 15+ years, and have an acute ability to recognize what creates sounds. Therefore, I believe that, with God's help, progress can be made.
Can you please give recommendations as to how I could get started on working with our priest on improving his accent when speaking English? For example, some helpful text we could work out of, or ways in which I could help, would be of great help to me.
Thank you very much for your service, and for your kind consideration.
I taught English in the Peace Corps in Nigeria for a couple of years and have interacted with Nigerian colleagues over the course of my career.
Let me first say that I agree with Professor Gupta that comprehension is a large part of the problem. Some acculturation of the American congregation to your priest's English would be helpful, and that should include acknowledgement of other standard varieties of English, of which Nigerian is an important one.
However, you can still help your priest adapt to American pronunciation. One of the most troublesome properties of Nigeria English for American listeners lies in the fact that Nigerian English is at the extreme syllabic end of the timing continuum. Languages vary on this continuum as to whether timing is tied to syllable length or to overall rhythm. In American English--and British-based varieties--timing is tied to rhythm. That is, our major stresses occur at roughly regular intervals. My fellow phoneticians know how much that statement needs to be unpacked, but that's not relevant here. In Nigerian English, all syllables have about equal length, and it sounds as if there is no or very little stress. To the American ear, that produces a very distinctive sound and one that is unexpected and difficult to comprehend. There is a sizable ESL literature on pronunciation, especially as it deals with stress patterns, and I would refer you to some of the techniques that are presented in that literature, even the older Jazz Chant exercises, which can be fun as well as instructive. Closely related to syllable timing is that, as Prof. Fidelholtz noted, English reduces unstressed syllables to schwas and shortens them, sometimes combining several written syllables into one or two spoken syllables as in casual speech reductions of phrases like "am going to." Nigerian English does not reduce syllables at all, and lacks the schwa vowel. Learning syllable reduction is a crucial part of learning the prosodic patterns of American English. In effect, in English in a stressed syllable the sounds are fully pronounced, but the unstressed syllables are reduced to fit between the rhythmic stress pulses.
One further consideration related just to vowel sounds is that Nigerian English is what is called an r-less dialect, like much of British and some US East Coast and Southern varieties. It does not pronounce the sound /r/ if it occurs after a vowel. What it does there is usually to substitute a full /a/ for the /r/, so that "near," for example, becomes "neeah," two syllables.
These are matters I would pay special attention to. Some work in these areas together with some listener acculturation should improve comprehension considerably.
Just a final note. Changing from the timing of one's native language, and most Nigerian languages are strongly syllable timed, is very difficult. We begin learning our mother tongue's timing patterns in the womb by hearing the rhythmic patterns and melodies of our mother's speech. In effect, we're born with our accentual and prosodic patterns, and that makes them hard to change. Speakers of American English deal with the inverse of the problem when learning a language like Spanish or French.
Good luck with your efforts, and don't give up!