Can Capacity Down disrupt Accelerator's esper powers? Capacity Down is a device that produces a sound that can disrupt an esper. It was used in the anime series against Kongou Mitsuko, Misaka Mikoto, Shirai Kuroko etc. 

My question is, does this device work against Accelerator, whose power can deflect any vectors who reachs him, and being sound waves used by the device also vectors?
Seeing as Capacity Down functions off of sound waves the answer actually depends.

If Accelerator is aware of it or is for any other reason reflecting sound waves away from him then no, it won't have any effect. If however he is taken by surprise and is not reflecting sound waves then it would work. He would hear it and it would prevent him from using his abilities to reflect it away from and also shut down his other abilities as well.