We know that irrevocable is pronounced with emphasis on the first e and not on the o as many people say. It would be logical to assume that words like irreversible, irreparable, etc., would follow the same rule. What is the correct pronunciation of those words?
When it comes to words that begin with the prefix ir-, stress varies.
Like the prefixes in-, il-, and im-, ir– is a negative element meaning “not.” It’s used in front of words that begin with r.
Sometimes U.S. and British English differ as to where to place the stress in the same word.
irrevocable (Merriam Webster gives the pronunciation irreVOcable)
irrefutable (Fowler and the OED acknowledge the pronunciation with the stress on REF, but prefer to place the stress on the FU.)
When in doubt, look up the word in the OED for the preferred British pronunciation, or in Merriam-Webster for the most common U.S. pronunciation.
A useful free online pronunciation source can be found here.