This paper reports an experimental investigation of the pollutant emission and noise radiation characteristics of both open and impinging inverse diffusion flames (IDFs), produced by five burners of different air port diameter (d(air) = 5,6 and 6.84 mm) and air-to-fuel spacing (S = 8, 11.5 and 15 mm). The effects of d(air), S. overall equivalence ratio phi and nozzle-to-plate spacing H on the pollutant emissions of CO and NO(x) and the noise radiation are examined. The results show that at fixed air flow rate, a smaller d(air) curtails NO(x) emission but augments noise radiation, indicative of a role played by turbulence, which tends to decrease pollutant emission and increase noise radiation. A larger S reduces NO(x) emission but increases noise radiation, indicating that different flame zones may be responsible for pollutant emission and noise radiation. When the IDF is under stoichiometric phi = 1.6, both the NO(x) emission and noise radiation are highest, as a result of maximum heat release rate. A comparison of EINO(x) for the open and impinging IDFs shows that the impinging IDFs emit more NO(x) probably due to the absence of NO reburning. The impinging IDFs have higher noise radiation than the corresponding open IDFs. A higher level of noise radiation from the impinging IDFs is observed as the target plate is brought closer to the burner. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.