The audible broad‐band noise generated by the discharge of high‐velocity gases into a relatively static medium can be reduced by effectively changing the discharge area to a multiplicity of smaller jets. Therefore, the normally audible noise is partially transformed into the inaudible range. The MULTI‐JET, essentially a perforated colander, utilizes this principle. To obtain satisfactory performance with this type of diffuser, it has been found necessary to match accurately the diameter of the colander to that of the jet‐exhaust nozzle. This matching involves a careful correlation between the diameter of the engine nozzle and the diameter of the colander together with the proper spacing between the nozzle and the colander entrance so that a close coupling is realized. Field tests have proven that maximum performance is obtained when the diameter of the colander is equal to or slightly larger than the diameter of the jet. In view of the many engine configurations presently operational and in view of continuous changing engine types, maximum utilization of a single colander cannot be realized. In addition to degradation in acoustic performance, mismatching also engenders other problems. In the case of an oversized colander, “boom” phenomena have been observed. In addition, backflow is created. This backflow causes temperature rise that complicates engine calibration and may even damage engine accessories. Aside from the problem of mismatching, present colander‐type suppressors have limited use. During afterburner operation, exhaust temperatures reach the neighborhood of 3000°F. Therefore, it has been the practice to employ the MULTi‐JETS only during the so‐called military operation of the engines. This limitation has persisted, notwithstanding the attempted uses of a liquid coolant, since severe thermal shocks generated by application of coolant produce rapid suppressor deterioration. The aeroacoustic‐flow diffuser evolved from a series of design and through numerous field tests has resolved the three major problems: acoustic performance, aerodynamic capacity, and structural durability. Field experience and test data relevant to the final design of a water‐cooled aeroacoustic diffuser are discussed.