How to get Text to Speech to pronounce phonetics and all the individual letters sounds

Hello,

I am developing a course for English learners and I need some way of getting the text to speech to pronounce phonetics that are taught in phonics. By this, I mean short vowels such as ă, ĕ, ĭ, ŏ, ŭ, combined vowels like 'ou' and consonant sounds such as sh, ch, th, ow, ck as well as all the individual alphabet letter sounds. Is this possible, and if so, what do I type?

Thanks,

Joshua