The audiofile is distorted and in reverse. It says:

Hello dear Cryptofriend,
as you can hear i'm outside
Can you tell me where I am right now?
I need to know.
I will send you a picture of my location.
Do you know what this could be, and where?
Thank you my friend, I'm waiting for your response.

And before I forget to tell you, you know in which city I live, just have a look at my introduceyourself post. And I see a building with a lot of satellites on it. It says "studio". I can see some rails, probably trains.

--> He lives in Hamburg