I have just come on for help on the same problem. I sometimes get a sound and sometimes don't.
I also have a problem with creating texts. I prefer to use the phone keyboard rather than the qwerty and do predictive text but when a word is not recognised I have to keep going into settings and changing into normal letter by letter text to write it. Also I know there is a way to add the word for use the next time but as soon as you turn your phone off it is wiped from the memory.