skribs
Grandmaster
I've seen Karate instructors teach "kiai" for use as a kiai, as well. I've always preferred "ha" (and "roy" for softer kiai, where there's no hard start or stop - more a practice technique than for common use).
I never learned it as a specific word or pronunciation. That was never its intended purpose. To help people learn how to use it I will tell them it literally means "expulsion of air". I know this isn't correct per the definition but it is for the purpose. I use the comparison of the sound we make when lifting something really heavy off the ground. More in the category of a grunt. It is using the deep, alveoli air from the lungs.
I actually prefer something that ends in a T because it gives a finished effect. A lot of the kids will let their "ha" turn into "haaaaaaaaaaaaaaaaaaaaaaaaaaa". Or they get the initial burst of air for half their kiyhap, but then the second half just trails off.
I think it's good when people develop their own kiyhap. But sometimes it helps to have a standardized sound so people know what's expected.