Hi Cmjkxa,
I don't know if you're still having the issue but I just thought I would throw my 2 cents in and see if it helps...when sending the sound n shot image to the other S4 can you get them to download the image to your gallery and then view it from there. I think that the image needs to be saved first before you'll be able to hear the sound along with the image.
Let me know if this works,
Cheers