What is the ruling on inaudible blowing during prayer according to Abu Hanifa's view?

Primary text

Abu Hanifa's position implies that blowing which a person cannot hear themselves is not considered to be blowing that invalidates the prayer, provided it does not form two letters. However, this is rejected because what invalidates the prayer when manifested (audible/articulated) must also invalidate it when concealed (inaudible/unarticulated), unlike speech.