Text to speech inconsistencies

Hello,

Looking for any suggestions on why and/or how to fix text to speech. I have an acronym... CPET (pronounced 'sea pet') in a module I am developing.  Sometimes the narrator sounds like they are saying 'pet' but other times it sounds like 'pit' and it doesn't seem to matter how I write it out. I have used 'c (space) pet', and 'sea pet' and either way I have the same issue. Sometimes it sounds fine, sometimes it does not. HELP! It's the primary acronym of the training module and essential that it sounds correct.

TIA!