
Originally Posted by
lauralie2
Some speakers say [prəˈpɔː.ʃən], some speakers say [prəʊ pɔː.ʃən], some speakers say both.
The second pronunciation ([prəʊ pɔː.ʃən]) involves a phonetic process called regressive assimilation. That's when a sound is assimilated in either manner or place to an oncoming sound. For example, the speaker in anticipating [p] in prəʊ pɔː.ʃən produces [əʊ], a vowel sound (between /u/ and /ə/) that shares articulation features with [p], namely a degree of rounding of the lips.
There's another pronunciation, one involving inversion or a switch: [pərˈpɔː.ʃən].