Is it wrong to pronounce the second "T" in word "potential"?

Potential is usually pronounced /pə'tenʃl/. However, many native speakers, and learners as well, will put a /t/ in between the /n/ and the following /ʃ/. This is called /t/-epenthesis.

This phenomenon will happen very often in English when we have /n/ followed by /ʃ/. So it is perfectly possible to say /pə'tentʃl/ in English. However, notice that this is not because there is a T in the writing. We also find an epenthetic /t/ in words like mensh where there is no orthographic T, no written T, between the N and the following SH, which represents the /ʃ/ phoneme.

An epenthetic /t/ is caused by the velum rising to make the /ʃ/ sound before the oral closure for the /n/ has been released. In other words, as we pass from making the nasal sound to making the 'sh' sound, our tongue and velum may be slightly out of sync. In the in-between phase the articulation becomes the same as that for a /t/, and so we get an incidental /t/ in the word.

We find the same thing when we get /n/ before an /s/, so the following words sound identical for many speakers:

• mince/mints
• prince/prints