Testing a 3-episode sponsor read streak to see if churn is the read or the show

I'm trying to separate two things before I decide anything: are listeners leaving because of the ad reads, or because the episodes themselves are patchy? So for the next six weeks I'm running the same sponsor read in the opening three episodes of the month rather than one, and asking the two sponsors I actually have whether they'd rather pay less for a streak. Small sample and I know it.