1. Otherwise phonetically complete English uttered on only one tone
'Even poor unfortunate monks and nuns in their
holy monasteries and convents must surely get so terribly bored with
singing the whole time at just one single pitch level that usually if
only at the very end of what they are singing they make at least a very
''slight 'change 'of 'pitch.
2. Otherwise phonetically complete English using only one vowel sound
[ə]
It's perfectly possible for anybody to talk English in a fairly comprehensible manner
for a considerable length of time without causing much difficulty at all to those who're
listening to them even though they're making use of only one single vowel phoneme.
3. English uttered on one vowel quality with one consonant
(e)
The Lord's Prayer
Our Father, which art in heaven,
Hallowèd be thy name.
Thy Kingdom come,
Thy will be done,
On earth as it is in heaven.
Give us this day our daily bread.
And forgive us our trespasses,
As we forgive those who trespass against us.
And lead us not into temptation,
But deliver us from evil.
For thine is the kingdom,
The power and the glory.
For ever and ever.
Amen