This aerodynamic mod was done on a gen 1. You might post there. I don't think wiper wind noise is a big issue on gen 2. Road noise is a much louder. Tires make a big difference here. Now if you had squeaky wipers I would say try silicone blades.
I don't own Gen1/2 and hopefully there are no squeaky bearings on 2014 Prius C yet. But wiper wind noise is apparent.