David J. Thompson

Sound radiation from high-speed railway slab tracks is commonly predicted using the two-and-half-dimensional acoustic boundary element method (2.5D ABEM), assuming longitudinally uniform acoustic boundaries for the structure. This assumption neglects the presence of the discretely distributed fasteners between the rail and slab, and the acoustic consequence is so far unknown. In this paper, the recently developed periodic acoustic boundary element method (PABEM) is introduced and applied to investigate the sound radiation characteristics of a typical high-speed railway slab track considered as an infinitely long periodic structure, fully taking into account of scattering effect of the periodically spaced fasteners. Acoustic dispersion curves, radiation efficiencies, and far-field sound pressures are predicted for waves propagating in the rail at different frequencies and wavenumbers, and the results are compared with those from the 2.5D ABEM model. This reveals the significance of the scattering effect of the fasteners that may make a rail wave radiate far-field sound efficiently despite the 2.5D ABEM model predicting no far-field radiation. These results highlight the importance of including the periodic boundary feature when predicting the sound radiation from slab track systems. A parametric study is then followed to investigate the effect of rail-slab gap on the track’s acoustic behaviour, including far-field sound pressure levels radiated from the track which is excited by a harmonic load moving along the rail. It is shown that, by fully acoustically blocking the rail-slab gap, the rail-radiated noise can be significantly reduced.

The Institute of Sound and Vibration Research (ISVR) at the University of Southampton was founded in 1963 from the Aeronautics Department. It grew rapidly into a leading centre for noise and vibration, combining research, teaching and consultancy. Although the initial focus was on the noise from aircraft and on their vibration-induced structural fatigue, there was already a recognition of the wider issues of sound in society and its subjective and medical effects. Consequently, the research interests of the ISVR quickly expanded to include aeroacoustics, automotive noise, structural dynamics, vibroacoustics, human responses to sound and vibration, data analysis and signal processing, active control, underwater acoustics and railway noise and vibration. The ISVR was a pioneer of university-industry collaboration, having many faculty positions that were supported by industrial funding as well as a strong consultancy activity. Unusual for an engineering department, teaching and research in clinical audiology featured strongly, and led to the establishment of a Cochlear Implant Centre in 1990. The paper gives a review of achievements of the ISVR in the 20th Century, identifying some of the main researchers and engineers who have inspired and guided its activities.