I have loud Vance & Hines 2 into 1.

I crossed a drawbridge today, with some sort of open steel road surface (like a hollow honeycomb). While I crossed the bridge, my noise dropped to almost nothing.

My question: is the noise I get in the highway bouncing back up from the asphalt and if my pipes are straight out the back, where would any bounce come from.

Any physicists out there that ride?

 

Can't explain it, it just is. When you cross an overpass with solid concrete sides it gets louder. I'd imagine that the more there is to bounce back the sound wave the louder it will seem to the rider.

 

That is exactly it.

Ever notice that when there are concrete barricades up the noise gets louder??

 

The soundis bouncing off the blacktop all the time, when you crossed over the expanded steel of the bridgethere is less surface to reflect sound waves back at you. It works just like a baffle in a set of drag pipes, as the sound waves travel down the pipe and gets to the baffle that is full of holes less sound is directed out the end of the pipe because it redirected through the holes. Just like at the bridge

 

Picture the sound waves coming out the pipes like concentric rings getting larger in diameter as they leave the pipe. If the ring gets the point that it doesn't hit anything to bounce back then it will just quickly fade from your ears. But, stand on the other side of the bridge and have a buddy ride your bike over the bridge and then it will sound just as loud.

It is strange that the sound to the rider drops, but the spectator fishing on the bank doesn't notice a sound difference.