One option would be to plug your lights into a sound-activated outlet. I use one every year and have hooked all my lights up to it. You can adjust the sensitivity of the mic so that while it's quite, the lights are off, but as the music (or talking trick or treaters) picks up, the lights flicker and get bright. Like a modified "Clapper" from the 80's. Here's a link to a DIY version, but over the years, a few companies have sold them. I picked mine up from Target about 6 years ago and it still works great.