Looks like a Sabertrio Arclyte.
Yes, you can add sound to it. They should be the same inner diameter as MHS parts from The Custom Saber Shop, so any electronics chassis parts from there or of that size (such as the 3D printed ones on Shapeways) should fit.
Since it doesn't have sound right now, you'd need to replace all of the internals. They use a 3w single LED in their stunt sabers, and with sound you'd likely want a tri-LED that supports Flash on Clash instead. And being a stunt it will currently have a latching switch, so you'd need a momentary switch instead. If the battery is an 18650 Li-Ion you can reuse it, but if it has the 4x AAA pack you'd need to replace that with an 18650.