I built a shower curb for my shower with standard practice:

tripled up 2x4's with dried wood for the boards, membrane wrapped over and secured only on the outside, and metal lathing wrapped over and secured on the outside. The curb is approximately 1/2-3/4" thick on the inside and outside and approximately 1" thick on the top.

However, what concerns me is that the curb sounds hollow. This makes sense in its construction as the concrete is a shell around the wood framing, and it sits on the membrane, but has no positive locking or bonding to the membrane. However, my intuition tells me that hollow sound is always bad (tiles, etc.)

I am going to let it cure for several days then put some foot traffic on it while working plumbing in the shower, so hopefully any failure of the curb would happen then and not down the road after tiling it.

Is this correct to sound as it does? Am I missing anything? I must have found a dozen articles/videos on how to build it, and I am fairly certain I covered all of my bases. Maybe I am just overly critical and nervous?

Thanks in advance.

The curb is built correctly. It sounds hollow because as you indicated.... it is hollow, but it will surely break apart with foot traffic. It needs to be protected until it's ready to be tiled.
Deck mud and fat-mud are both not meant to stand up to heavy traffic ... especially something as open and vulnerable as a curb construction. The characteristics that make it perfect for tile, make it terrible for direct wear and tear.

Thanks for the info, it just seems counter-intuitive to me. I will keep light on it until I tile it.