Purpose of giant yellow foam blocks in doors?

[chuyler1]

I was browsing photos of someone's install when I came across a familiar object. A giant foam block in the door panel. I had these in my Mazda Protege5 too. What are they and what purpose do they serve?

http://www.mp3car.com/vbulletin/attachments/worklogs/41615-2006-mazdaspeed-6-sound-quality-competition-car-door-window.jpg

[Slick]

Side impact. Funny thing is, I actually quoted on that block out of another foam material when they were going to switch from eurothane :)

[copenhagen]

don't listen to him...its to tell you what to take out to mount a crossover:liar: