Finally had some time to 'try' and capture the sound... Will try to make another soon with a descent camera!
In the video, I'm driving over severel small holes (3) in the road. But you can here it also when you ride over 'the tar between the concrete plates'
Don't know if anyone will understand me but I'm doing my best (I'm from Belgium btw). The sound comes from the left side (Left Handed car here), I think somewhere arround the hood release orso...
http://www.youtube.com/watch?v=rUvVOBXtAZg