A description is given of the construction details of the Sound Laboratory recently completed by the Parmly Foundation at Technology Center, Chicago. The function of the laboratory is to carry out research in the prevention and alleviation of deafness. The chief feature of the laboratory is an echo free or “anechoic” chamber. The 40‐ton chamber of concrete, steel, wood, and sheet‐rock construction is suspended on Neoprene pads to have a natural frequency of about four and one‐half cycles per second. Continuous ventilation through ducts of high sound attenuation, 90 db at 128 c.p.s., is provided. The inner surfaces are designed to have 99 percent absorption or better at 115 cycles per second or above. The Harvard treatment of wedge‐shaped Fiberglas is used. The chamber is housed in a concrete block wing, the walls of which are lined with Fiberglas sheets. Costs in terms of man hours are given.