I didn't hear it
I do hear it
pro:sub mod v pro:per
i didn't hear it .
aɪ WORD_BOUNDARY d ɪ d n t WORD_BOUNDARY h ɪ ɹ WORD_BOUNDARY ɪ t WORD_BOUNDARY
i WORD_BOUNDARY d i d n ' t WORD_BOUNDARY h e a r WORD_BOUNDARY i t WORD_BOUNDARY