What can we do?" asked the distraught mother. "We live in an apartment and our ninth-grader plays the drums. We stapled egg cartons over the entire ceiling and walls in his room, but the neighbors still complain." Just because egg cartons resemble sound-absorbing wedges doesn't mean they will endow your living room with the acoustical properties of a recording studio. Even though cardboard will absorb more sound than plaster, and the irregular shape will scatter the highfrequency sound, the main attraction of egg cartons is low price. The egg-carton story illustrates two common pitfalls in solving acoustical problems. The first mistake was to use a The keys are adding mass and making resilient connections by Timothy Foulkes Wood framing is extremely