You have to play along...

You have to use noise canceling headphones and the room needs to be quiet for best results. If you can hear yourself over whats coming through the headphones, it wont work even a little. It helps to read something and try and talk in long sentences instead of just short comments. It isnt actually going to keep you from speaking or forming a sentence, so you have to play along. The delay is supposed to make it confusing to finish a sentence but its not difficult to ignore the delay and just speak normally. If you want to have fun with it, you need to quit trying to be cool and beat the system and just listen to the delay and let it confuse you. It can be funny if you play along.

BranVsWild about Speech Jammer, v2.0.1