I believe there is an audio conversation in German by ISS Commander Alexander Gerst in this audio segment captured. There is a lot of static background static noise, I removed some of the noise with Audacity and its noise removal tool to try to clean it up a bit, and German can be heard. As there is only 3 people onboard the ISS currently a Russian and a Woman being the others. I believe this is the ISS Commander having a chat
If anyone can hear what’s being said in German? If it’s not a private call home etc. Would be interested to know for curiousity sake.
The waterfall plot of your observation shows that you have more than enough sensitivity to demodulate it, but unfortunately there’s a -9kHz frequency offset of your receiver, so the signals are just outside the 8kHz low-pass filter that is applied before storing the audio.