Here's a breakdown:
* tet: like the word "tet" but slightly shorter
* ee: like the "ee" in "see"
* ah: like the "a" in "father"
* roh: like the "row" in "rowboat"
* ah: like the "a" in "father"
It's important to note that the "a" sounds in "Tetiaroa" are all pronounced the same, like the "a" in "father".