Improving the intelligibility of underground station public address / voice alarm systems using horizontal line array

Abstract

As London's extensive underground network passenger communication is highly dependent on its Public Address/ Voice Alarm system, attention to its efficacy is of great importance. In its current state, the system lacks 21st-century performance which could be implemented using modern technologies. Underground station currently struggle to achieve the minimal life safety intelligibility requirements established by the British standard and bringing an uncomfortable experience to millions of daily passengers. A reinterpretation of the line array / planar source concept in computer simulations has been used to raise the intelligibility beyond the minimal requirements by achieving a homogeneous sound distribution close to the public, with minimal room excitation. This approach minimises destructive reverberant interference and hence proves to improve intelligibility.