i made a sound reactive chain of WS2812 lights with table tennis balls and i control it with a sound sensor and an arduino. This is a easy project which beginners can do.
Step 1: Circuit
I connected the WS2812 LEDs like in the picture. Dont forget that you cant supply too much LEDs with the arduino. Use a separate power supply therefore. I used a 470 Ohm resistor in series for the data line, and a 1000uF capacitor (at least 5V) in parallel with the supply.
I got the sound sensor here:
But you can also get it anywhere else. You also can get the WS2811 LEDs and the other stuff at many shops.
Step 2: Programming
To control the LEDs you need the Adafruit library which you can get here:
Because the sound sensor only gave me a high or a low level signal, I take 100 analogValues from this sensor and count how often they are high. Through this relation I can control how many LEDs shall be turned on.