ok, so this is the last thing I am going to say about this, because we are not at all answering this man's question. But mass equals sustain in the bridge or block because...the strings transfer energy to the block. This sends the molecules that make up said block into a tizzy, crashing into one another. If the block is made of a less dense material, the molecules have to travel farther in between collisions and hence lose energy. In a block made of a more desne material the collisions happen more frequently, in essence prolonging that sweet bent A note!
Now, do we all hear this, does it make that much of a difference, well I think it makes some difference, but so does every thing else.