The ear drum is a thin membrane that is designed to move with the slightest energy transmitted through/by the air. The brain and skull have much more mass and support structure that holds everything in place. Moving air will not impact the skull/brain.

I did not say that longer dB's are more damaging to the brain. Longer impact forces are. dB's are not really impact forces. They are vibratory forces in the air. The air moves back and forth very short distances. Air can easily move the thin membrane of the ear drum. It takes far more energy to move the skull and/or brain matter.

The ear drum has a mass similar to paper. It does not take much force to move paper. But, you could not flap a piece of paper at the skull and cause any impact to the skull. Sound travels at about 1100 feet per second. For air to transmit enough force to cause damage, the shock wave would need to travel much faster or have far more energy (dBs). 90 dB's does not even hurt the paper thin ear drum unless it is sustained over long periods where it can cause scaring/stiffening/thickening of the ear drum.

Without a basic understanding or weight and motion physics, I doubt you will understand these issues. Just try to believe me when I say the sound of billiard balls hitting does not injure the brain.