There is an rtl_433 project under which RTL-SDR software to decode a number of transmitters has been developed. Searching on rtl_433 will give a number of hits describing how various people reverse-engineered these signals.
My understanding is that the original poster has apparently captured a post-detection analog signal and needs to figure out how to extract the digital intelligence from this. My approach would be to read the .wav file into Matlab and play with it there, but that presupposes understanding that tool set.
Once the coding scheme has been cracked, it is likely that an Arduino based decoder could be built, but Arduino is probably not the right tool for figuring out the coding scheme.