Acoustic Environment Of The Ticket Office Of The Railway Station

A ticket office is an important function zone in a railway station.Without sound absorption material lined in the hall,much reverberation makes the sound pressure level high,speech confused,language communication in disorder and passengers and staff discomfort.In this paper a railway station ticket office is studied,noise reduction plans are proposed by measurements and simulations to provide the theoretical basis for noise reduction application.The sound pressure levels in the ticket office are measured,the reverberation time is measured by using the impulse response integral method,and the speech transmission index STI and Definition D₅₀ are calculated.It is judged whether the sound pressure levels are above the limit.The main noise source,spatial noise distribution,main noise bands reverberation time and the quality of speech intelligibility are analyzed.The sound in the hall is simulated by the acoustics software,and the model is validated by comparison of simulations and measurements.In the simulations,sound pressure levels,STI and D₅₀are analyzed in different functions.The plan is proposed with sound absorption,reducing the loudspeaker number and loudspeaker power.The main conclusions are as follows:The average sound pressure level in the ticket hall is 75.5 d B（A）above the limit of 70d B（A）.The main noise sources are the speakers at the ticket window and the ceiling.The percentage of low and mid bands is 99%.Reverberation is dominant in the sound field,and the reverberation time is 2.5～3.75 as long as the optimum time.Close to the source,STI and D₅₀are satisfied with the requirements of speech intelligibility,and far from the source STI is greater.The sound pressure levels,reverberation time,STI and D₅₀are in agreement in simulations and measurements.In simulations the sound pressure levels with two loudspeakers in use at the ticket window are lower 1～3 d B（A）than four loudspeakers in use.STI and D₅₀are about 0.5 close to the ticket window and from decreased to uniform far from it in measured background noise;STI and D₅₀are about 0.3,uniform and lower in the sound field radiated by the loudspeakers at the ticket window consider as the background noise;STI and D₅₀are higher close to the ticket window and lower far from it,and D₅₀decreases faster in the sound field radiated by the loudspeakers at the ceiling consider as the background noise.STI,D₅₀ and reverberation time are satisfied with the acoustic requirements in the hall with sound absorption materials of 353.04m² in three background sound fields consider of measured background noise,sound radiated by the loudspeakers at the ticket window and the sound radiated by the loudspeakers at the ceiling.By reducing a loudspeaker and the power of the loudspeakers power at the ticket window and the ceiling close to the ticket window,the sound pressure levels are lower than the noise limit.Sound field is hardly affected by absorption material positions in the same areas of materials and its effect is ignored.