Jonny R wrote:
I live in a residential neighbourhood about a 5 minute walk away from
a busy 4-lane road. I can normally hear the traffic from my house
when I have the windows opened (not too loud but definitely noticeable
sound of traffic). The other day I was going for a walk in the
neighbourhood about 1 minute away from this street, and was surprised
to hear how quiet it was. Noticeably quieter than around my house
that's 5 minutes away actually (you only heard the traffic if you
stopped walking and listened for a while). I told this to a friend
(who's an electrical engineer) who told me that it is possible for the
sound from the highway to hit the noise barrier and like a wave "rise
up", bypassing the houses that are nearby, and come back down on the
houses that are further away, where it will appear louder compared to
the houses in the middle where the sound travelled over. Here's a
drawing to help explain what he was trying to tell me. Pretend this
is an aerial view from above:

Spooky, isn't it? But yet, there it is.