University Classroom Acoustics Improvement Strategy Based On Measure For Speech Intelligibility

University classroom is an important place for teachers and students to learn,good listening environment is the necessary guarantee for students to learn.For various reasons,the classroom listening environment in China and the world is not ideal.To conduct the thorough research to the problem of university classroom listening environment is necessary,and the problem of classroom acoustic environment is also a hot topic in the field of architectural acoustics.To improve the classroom listening environment,we must select the appropriate objective parameters to evaluate classroom listening environment first.The classroom listening environment has been evaluated using traditional acoustic parameters(such as reverberation time,background noise,sound energy ratio,etc.).With the development of Speech Transmission Index(STI),it is possible to improve classroom sound quality based on STI.As compared to the traditional acoustics objective evaluation parameters,such as reverberation time,background noise,clarity C50,etc.,STI is able to consider the the impact of reverberation time and signal to noise ratio.It directly corresponding to subjective feeling,thus has the advantages which the traditional evaluation parameters do not have.Therefore,it is very meaningful to study the improvement strategy of classroom listening environment based on STI evaluation.The transmission of speech in the classroom is a complicated process.The volume of the classroom,the profile of the flat and the arrangement of the sound absorbing material will have different effects on the speech intelligibility of classroom.Therefore,based on investigation and analysis about the present situation of classroom acoustics,this paper systematically studies the design strategies to improve the speech intelligibility of university classroom.Combining with the acoustics simulation technology,these strategies are applied to the improvement of the sound quality of different types classrooms,and verify the strategies by subjective and objective evaluation.The main work of this paper includes the following contents:(1)Evaluated the classroom sound quality by subjective and objective evaluation,summed up the problems of classroom sound quality.(2)Based on the evaluation results,the correlation between different objective evaluation parameters and subjective evaluation is compared,and discusses the accuracy of different objective parameters for evaluating classroom sound quality.(3)Based on the STI evaluation method,the influencing factors of classroom speech intelligibility are studied.Including the volume of the classroom,the shape of the plane,the shape of the profile and the arrangement and selection of sound-absorbing materials.(4)Based on the research of influencing factors,the design strategies to improve the speech intelligibility of classroom.Through the sound quality simulation technology,the effectiveness of the design strategy applied to the improvement of classroom sound quality is carried out.The shortcomings and limitations of the strategy are discussed.This research has a good guiding significance for the application of speech intelligibility evaluation in classroom sound speech intelligibility improvement.