【作者】 王华；

【导师】 吴礼福； 王峰；

【作者基本信息】 南京信息工程大学 ， 电子与通信工程（专业学位）， 2018， 硕士

【摘要】 声信号在封闭空间中传播经墙体、天花和地面的反射后晚于直达声到达入耳或拾音器,形成拖尾导致清晰的语音变得模糊,这种混响现象给人们的语言沟通,语音通信系统等带来不便。随着科学技术的不断发展,去混响技术应用到越来越多的领域中,比如建筑声学、声源定位、语音识别等,混响时间是去混响过程中一个重要参数。而且,混响时间在厅堂音质方面的客观评价以及材料吸声量测量方面也有重要作用。混响时间测量方法有很多,其方法分为盲估计和非盲估计。其中盲估计法中使用最多的是最大似然估计算法,即采用说话人在房间中自然说话时发出的混响语音信号来估计混响时间的方法。本文提出了一种改进的最大似然估计算法,该方法首先确定语音衰减段的最优边界,其次计算该衰减段的两个额外参数,据此筛选出符合条件的语音段,最后将满足条件的语音段采用最大似然估计得到混响时间估计值,通过MATLAB进行仿真实验,实验结果显示改进方法估计的混响时间同真实混响时间的偏差更小,方差更低,估计准确性较高。为了将算法运用到实际的测量中,本文利用MATLAB GUI设计一个混响时间估计系统,该系统主要通过扬声器播放一段白噪声信号,再通过麦克风接收录制该语音信号,通过维纳滤波计算房间的冲激响应,最后利用施罗德脉冲响应反向积分算法和最大似然混响时间盲估计算法算出相应的混响时间,并将结果显示在系统界面上,两者计算结果基本相同,该系统实现了实时测量房间混响时间的功能。更多还原

【Abstract】 During propagation,Acoustic waves reflected by wells、celling and floor form faded tail called reverberation.Reverberation reach ear or microphone with direct sound signal and effect original intelligibility of speech and communicate systems.This reverberation will bring inconvenience to people’s language communication,voice communication system and so on.With the development of science and technology,dereverberation technology has been applied to more and more fields,such as building acoustics,sound source localization,speech recognition and so on.Reverberation time is an important parameter in dereverberation process.At the same time,the reverberation time also plays an important role in the objective evaluation of the acoustical quality of the auditorium and the measurement of the sound absorption of materials.There are many methods of reverberation time measurement,which are divided into blind estimation and non-blind estimation.The maximum likelihood estimation algorithm is the most used in blind estimation,i.e.,using the reverberant speech signal naturally uttered by the speaker to estimate reverberation time.An improved algorithm for blind estimation of reverberation time based on maximum likelihood is presented in this paper,Firstly,special rules for defining the optimal boundaries of the speech decay segments are introduced.Then,two additional parameters are calculated to select the speech decay segments for maximum likelihood estimation.Finally,the reverberation time is estimated based on the maximum likelihood estimation using the selected speech decay segments.The simulation experiment is carried out through MATLAB,and the experimental results show deviation and their variance between the estimated reverberation time and the true value are decreased.In order to apply the algorithm to the actual measurement,this paper uses MATLAB GUI to design a reverberation time estimation system.The system mainly plays a white noise signal through the loudspeaker,then receives the recorded voice signal through the microphone,and calculates the impulse response of the room through Wiener filtering.Finally,the corresponding reverberation time is calculated by using the Schroeder integrated impulse response algorithm and the maximum likelihood reverberation time blind estimation algorithm.The results are displayed on the interface,basically the same.Therefore,this system realizes the function of real-time measurement of the reverberation time of the room.更多还原