I was hired to provide music for a community skateboard/basketball-shoot-out event. It was outdoors and required two sound systems, each with different music play lists. In addition, each sound system had wireless microphones for the announcers. Rather than man both sound systems in order to turn down the music whenever someone spoke into the mic, I bought two duckers. A ducker fades out the music when someone speaks into the microphone and turns it back up when they stop talking. DJs use duckers. I mainly run live music events so these little boxes were something I never needed until the organizer asked for the feature. I was going to try to use my compressors as duckers but these looked easier and were made for the job.I sent my laptop (music) into the tucker. You'll need an audio cable that terminates with RCA jacks, which connects to the ducker. Your mic will connect to the ducker via XLR cable. These two signals are combined in the ducker and fed out as a single RCA cable. THIS cable will go into your sound board.To use, you will set your sound board level so it is somewhere reasonable to start the adjustment process. No clipping! Next, you set the music level via laptop..so you can hear it through the PA system. Then set the the mic level on the ducker. Speak into the mic and adjust the signal level on the ducker. You have to balance the levels out between the vocal mic and the music input. The overall PA volume is controlled by the mixer. Once you have the music and vocal signals sounding the way you want it..adjust the ducking level and sensitivity. The duck level sets how LOW the ducker turns down the music-a little bit or way down. The sensitivity adjustment regulates how sensitive the ducker is. In other words you don't won't the ducker to turn down the music every time the mic picks up background noise, crowd noise, etc. You want the ducker to work ONLY when someone speaks directly into the mic. I had to turn the sensitivity down because the ducker was responding to the music I was playing. I decreased the sensitivity so it only ducked when someone spoke right into the microphone. This little box also lets you adjust how quickly the music level comes back up once the person stops speaking. Total control.It helped to have an assistant speak into the mic, with the music playing, while I made the adjustments back at the PA system. You could do it yourself by trial and error. Speak into mic, make adjustment, try again, tweak, and so on.Overall this is an easy to use device that made my life easier and the customer very happy.