Airport terminals were once characterised by a cacophony of sound from gate announcements and plane noise to the myriad of conversations and footfall of the thousands of passengers that pass through each and every day. Achieving optimum levels of noise control in such a complex acoustic environment is a balancing act between ensuring the intelligibility of public address systems and controlling the noise of passengers whilst at the same time creating a constant level of sound that masks activities from cafes and retail outlets. What options do airport design teams have when it comes to controlling sound and ensuring the passenger experience is stress-free and greatly improved? Stuart Colam, Acoustics Advisor of SAS International, investigates.