Every experiment has a null hypothesis. For example:
ɛ v ɹ i WORD_BOUNDARY ɛ k s p ɛ ɹ ɪ m ə n t WORD_BOUNDARY h ʌ z WORD_BOUNDARY ʌ WORD_BOUNDARY n ʌ l WORD_BOUNDARY h aɪ p ɑ θ ə s ɪ s WORD_BOUNDARY f ɔ ɹ WORD_BOUNDARY ɛ ɡ z æ m p ə l WORD_BOUNDARY