You might find the electric freight trains are quieter than you expect. I did, in a place I lived in England.

There's a rail noise map for some lines in Denmark. Activate Temavælger - Jernbanerstøj - Større Jernbaner 1,5m, and start at Copenhagen Airport, the Øresund line might be similar.

https://miljoegis.mim.dk/modules/mobile/?profile=noise