Research On Prediction Method Of Speech Transmission Index Based On College Classroom

As the most important objective acoustic parameter to evaluate classroom speech intelligibility,the speech transmission index(STI)can comprehensively consider the influence of reverberation and noise on speech signal distortion.Using STI as the reference acoustic parameter for classroom acoustic design can ensure the classroom to achieve good speech intelligibility.However,STI usually requires actual measurement and complex evaluation,which is difficult to achieve in the early design stage of the project.Therefore,the accurate and fast STI prediction method is very important for the application of classroom acoustic design stage.In this paper,acoustic data measured in six college classrooms(36 measuring points)are used to verify and compare the three existing STI prediction methods,and the equation of using reverberation time(RT or T30)and SNR to accurately and rapidly predict STI is proposed.The main research contents are as follows:This paper use the sound simulation software ODEON of STI prediction methods based on impulse response simulation is studied,the factors that affect the precision of forecasting are discussed in this paper,including the sound-absorbing material absorption coefficient of the reduction process,the simulation problem such as the choice of the sound source,found in the sound field simulation and the actual sound field equivalent under the premise of good,predicted values and measured error is smaller;After that,the STI prediction methods proposed by Houtgast et al.(RT and SNR values need to be input)were verified.The RT and SNR measured and predicted in the classroom were used to predict STI respectively.Although the two STI prediction methods mentioned above can effectively predict STI,their complex use process and long calculation time cannot meet the need of designers to quickly obtain STI values when adjusting acoustic design schemes.In view of the problems in the above two STI prediction methods,some scholars put forward a simplified equation for rapid prediction of STI using RT.In this paper,six equations are selected for verification and analysis.It is found that the existing STI prediction equation will underestimate the STI of the measurement point closer to the sound source,overestimate the STI of the measurement point farther away from the sound source,and only make a rough estimate of the average STI of the classroom.Aiming at the problems existing STI fast prediction equation,this paper introduced SNR as fixed STI predicted results of the parameters,based on six universities classroom acoustic measurement data,try to use RT and SNR established STI fast prediction equation,and use the other three sample classroom prediction accuracy of equation is verified,the error of the predicted values and the measured values are within one JND.This paper systematically verified and analyzed three STI prediction methods,studied the problems affecting the prediction accuracy,and provided corresponding solutions,which can provide reliable experience for relevant researchers.In this paper,the STI rapid prediction equation established by RT and SNR has a high prediction accuracy,which can meet the needs of designers to quickly obtain STI values in practical engineering applications,and has a strong practical significance.