Okay, so i did the sound analysis of "listen to my voice" and here is what i got.
The whole sound looks like this: https://hkar.ru/OTR4
It doesn't make any image, but if you look at both ends of the spectogram you can see a difference with the rest of the picture.
So i enhanced both ends and here is what i got
Left end https://hkar.ru/OTR2
Left end with different settings: https://hkar.ru/OTR3
Right end:https://hkar.ru/OTR1
Right end with different settings: https://hkar.ru/OTR0
Okay now... the right end looks like morse code, but it is not apparent with the letters spacing. It could be treated as several different letters.
I didn't find anything that I could decypher at this point.