Characteristics And Prediction Model Of The Sound Field And Crowd Noise In Extra-large Spaces

With the construction of large-scale public buildings such as exhibitions and waiting halls of transportation hub,the interior acoustic environment of large spaces has become more and more important.The systematical research of sound field in extralarge space is more and more urgent.Although the inhomogeneity of diffusion in the sound field of extra-large spaces has been widely received,systematic research remains to be carried out.In this paper,through on-site acoustic tests,computer simulations and theoretical studies on different volumes of space,it has been found that the spatial distribution of reverberation time in extra large spaces is more uniform in extra-large spaces,and the values of EDT and T30 are also closer;The decay curve is more irregular near the source and some of them appears hyperbolic.The curve is more smooth and linear far from the source;The impulse response is sparse overall,and far more than the theoretical amount because of diffusion.The difference between sound energy and duration of early reflection and late reflection is very different;The spatial distribution of the Speech Transmission Index fluctuates as a whole.Lower value was obtained with the growth of volume.In this paper,through field tests,computer simulations and theoretical studies on different volumes of space,it has been found that the spatial distribution of reverberation time in extra large spaces is more uniform in extra large spaces,and the values of EDT and T30 are also closer;the decay curve is earlier in the near sound The attenuation at the source is more irregular,some appear hyperbolic,and the attenuation curve at the far source is more smooth and linear;the impulse response is sparse overall,and the reason for diffusion alone is far more than the theoretical amount.The difference between sound energy and duration of reflected sound and late reflection sound is very different;the spatial distribution of the language transmission index as a whole fluctuates.As a whole,the larger the space,the lower the measured language transmission index.The distribution of acoustic energy in the extra-large space has been explored.The total sound energy and reverberation sound energy both show the similar exponential attenuation characteristics.According to the importance of the first reflection from floor,an energy distribution prediction model for extra-large space is established.The effects of different acoustic parameters on the spatial distribution of supersonic spatial sound pressure levels were studied,and the effectiveness and limitations of noise reduction effects for sound absorption were found.Different position of sound-absorbing materials has different effect of noise reduction.The floor and the wall are relatively advantageous position,but it is also affected by the proportion of the space.The effect of noise reduction is a fixed value for the same height ratio in spaces with different volume,and the noise reduction value is lower in the extra large space.Air sound absorption plays an important role in the large space.Through on-site test and theoretical calculations,we have explored crowd noise in extra-large spaces and found that there is a strong correlation between crowd noise and people number.According to the aggregation of crowds in the seat area,we developed a test method for the average sound power of people in extra-large spaces.An large crowd noise prediction model have established based on the dissemination crowds;In the end,according to the previous chapters,we propose design strategies for acoustics,electroacoustics,and noise reduction in extra-large spaces.The research in this paper is only a preliminary exploration of some basic characteristics of the large-space sound field,and the evaluation of the energy decay,the subjective evaluation of the acoustic environment,and the influence of other factors have yet to be further studied.