Audio Steganography: Inaudible Audio Watermarking for Source Identification
Petrus. First of all, thanks for attaching my github library as an update into your question for other readers. I have just seen your question.

According to my own experiences, echo hiding methods are fragile towards additional echoes, so are towards reverb. A simple spread-spectrum model using a PN Sequence, which introduces some noise, embeds data into high-frequency bands, so hidden data is usually audible and not robust against low-pass filters. 

Transformations such as cosine transforms and wavelet transforms are often used in audio watermarking. Applying a spread-spectrum method without a PN Sequence onto Approximation Coefficients of the third level wavelet decomposition (A3) would be very robust against many common attacks except high-pass filter, and would be almost completely imperceptible. On the other hand, hiding data onto Detail Coefficients of different levels, gives different balance between robustness &amp; transparency. These decompositions are done very easily in Matlab if you have Wavelet Toolbox. However, I have not uploaded my related works into github yet.

We have not worked with real-time audios, but I know that all of these techniques can be applied for them as well. I am not sure whether you already solved your problem, but if you have any further questions you can point out in a comment. I am not an expert in digital signals unlike many of you on this site, so different opinions are also very welcomed. 

Best Regards.