[Weasel9992]

Originally Posted by foxfyr

What they said above.

Put very simply...

Traps dissipate acoustical energy as heat.

Thus, the more velocity the wave exhibits, the greater the dissipation of energy.

The velocity of the wave at the incident wall surface is zero (think of tossing a ball straight up into the air, and at the moment of its maximum altitude, the upward velocity goes to zero, before reversing direction and falling with increased downward velocity).

Thus, the region closest to the wall is not as effective in dissipating the energy and velocity as the region further from the wall.

So, while the added mass will certainly increase the total dissipation of energy if filled in closest to the wall, the % increase in the results diminish.

Stated another way... you get the maximum return on investment with a spaced bass trap, although the total space filled with the trap would perform incrementally better, but at higher material costs.

That was a great post. Very well explained!

Frank