I think there are noises specific to railways. And from what I believe this "MetaWindow" targets relevant frequencies.
However, I am sure this also works for the frequencies generated by car traffic.
At least the linked youtube video in this comment [1] does not mention anything about frequencies.
At least the linked youtube video in this comment [1] does not mention anything about frequencies.
[1] https://news.ycombinator.com/item?id=40384778
EDIT: I was wrong about the video. There is _no mention_ about frequencies.