Particles are known to be typical characteristics of spontaneous speech. Their function is to modify the content of the statement, to structure the sentence and to ensure contact with the listener.
Both chápeš and rozumíš belong to this group: their form suggests a request for attention or reaction. An analysis of the spoken corpus ORAL2013 shows a rather sporadic verbal response by the listener.
Their position in the text is not random, they typically occur at sentence-borders or in front of the word that should be stressed.