Rolling Thunder, a motorcycle parade in its 22nd year, roars across the Memorial Bridge to make a circuit of the Mall before terminating at the Vietnam Memorial. Vietnam vets ( Desert Storm and Iraqi Freedom vets as well) ride their hawgs to bring attention to POW's and MIA's, and veterans' rights in general.
Curiously though, the noise becomes part of the background. I found a way to tune out the rumbling. The occasional rip of a revving engine breaks out of the background sound profile. Otherwise the sound which seeks a temporary occupation of the space of the Mall just sounds like loud, annoying traffic. The occupation happens physically in the barriers erected by the police to allow Rolling Thunder to pass through.
I am left wondering what the noise is saying. Listen: