人工混响算法

详细介绍了人工混响的裳和算法及其特点，并用Matlab在微机上对各种算法进行了仿真，取得了很好的效果。最后提出了算法的改进方向。     

基于DSP的实时数字音效处理系统

论述了基于DSP56F826 EVM开发系统的实时数字音效处理系统，在对数字音频信号的混响、合唱、均衡等多种音效方式合成的原理和算涪研究与仿真的基础上．在硬件上实现了这些音效的处理．并能够实时处理后播放。     

Reverberation time measurements in non-diffuse acoustic field by the modal reverberation time

The increasing presence of low frequency sources and the lack of acoustic standard measurement procedures make the extension of reverberation time measurements to frequencies below 100 Hz necessary. In typical ordinary rooms with volumes between 30 m³ and 200 m³ the sound field is non-diffuse at such low frequencies, entailing inhomogeneities in space and frequency domains. Presence of standing waves is also the main cause of bad quality of listening in terms of clarity and rumble effects. Since standard measurements according to ISO 3382 fail to achieve accurate and precise values in third octave bands due to non-linear decays caused by room modes, a new approach based on reverberation time measurements of single resonant frequencies (the modal reverberation time) has been introduced. From background theory, due to the intrinsic relation between modal decays and half bandwidth of resonant frequencies, two measurement methods have been proposed together with proper measurement procedures: a direct method based on interrupted source signal method, and an indirect method based on half bandwidth measurements. With microphones placed at corners of rectangular rooms in order to detect all modes and maximize SNRs, different source signals were tested. Anti-resonant sine waves and sweep signal turned out to be the most suitable for direct and indirect measurement methods respectively. From spatial measurements in an empty rectangular test room, comparison between direct and indirect methods showed good and significant agreements. This is the first experimental validation of the relation between resonant half bandwidth and modal reverberation time. Furthermore, comparisons between means and standard deviations of modal reverberation times and standard reverberation times in third octave bands confirm the inadequacy of standard procedure to get accurate and precise values at low frequencies with respect to the modal approach. Modal reverberation time measurements applied to furnished ordinary rooms confirm previous results in the limit of modal sound field: for highly damped modes due to furniture or acoustic treatment, the indirect method is not applicable due to strong suppression of modes and the consequent deviation of the acoustic field from a non-diffuse condition to a damped modal condition, while standard reverberation times align with direct method values. In the future, further investigations will be necessary in different rooms to improve uncertainty evaluation.     

超长混响超大容积玻璃大厅声学改造实践

结合超长混响超大容积玻璃大厅建声和电声设计的具体案例,探究因受特殊使用的需求、技术实现等客观条件所限,无法用建声来解决所有声学问题时,如何用电声补救建声的不足,提高厅堂语言扩声的清晰度。     

基于RHC-7水听器对液体中固体目标声波探测研究

为了实现液体中微小固体目标在线探测,设计了基于RHC-7水听器采集系统探测液体中微小固体目标的新方案。探测系统利用脉冲激励瓶体产生混响声波,RHC-7水听器浸入瓶内液体中采集声波,经UTC1250VA带通滤波器放大滤波后,对采集的混响声波信号进行Mallat多分辨率时频分析,分离提取微弱的探测目标信号。由于液体中固体目标粘滞声吸收和散射声吸收会影响水声信号的频谱分布,计算探测信号各频段频谱与基准信号的相关度,确定检测阈值,并作为识别瓶体中有无固体目标的指标。实验表明,该方法简单、实用,可实现探测一定尺度的悬浮和沉淀目标。     

贵阳六万座体育场STIPA设计探讨

体育场馆扩声系统从设计到调试,首要目的是为实现语言可懂度,其次是音乐丰满度。也就是在客观声场环境下,能实现STIPA平均值及五大指标的招标要求。通过对贵阳体育场的封闭EASE模型后的计算机声学模拟结论,与第三方检测结果做对比分析,针对"有必要制定STIPA空场测点最低下限值"问题展开讨论,希望制定出STIPA相应合理的统计标准。     

室内声环境中的语音端点检测自适应算法

室内场所是语音识别技术的一种典型应用环境,传统的端点检测研究多考虑噪声的影响,忽略室内混响的影响,研究证明室内混响对端点检测和识别效果能造成显著的负面影响.通过研究短时能量和短时自相关序列( RAS),提出了一种自适应的端点检测方法.可以通过估计噪声段短时能量来适应平稳噪声干扰环境,并能修正含混响语音的检测终点.端点检测和语音识别实验结果表明,本方法在平稳噪声和室内混响声环境下具有良好的性能.     

浅谈广播电视中心的声学设计

广播电视中心工程建设不同于一般商务办公大楼建设,它涉及多种学科,声学装修是其中的一个重要部分。要得到一个高保真、有良好声学效果的演播室,不仅要有一套好的音响及录、播音设备,而且还要有一个良好的声学环境。根据现行行业规范介绍了演播室、录音室和导播室建设的技术要求。具体给出了其声学装修方案．同时介绍了安全环保的新型建材,并给出了工程实例。     

可导向阵列扬声器系统的发展与应用

可导向阵列扬声器主要解决混响时间过长等声学不良条件下的语言清晰度差的问题和提高听感质量。介绍了几种典型的可导向阵列扬声器系统的发展及其在多功能厅、高级会议厅扩声中的一些应用实践。     

短脉冲激励的混响室设计

根据理想封闭矩形腔体内电磁场表达式,分析了对混响室内场特性有影响的因素;结合混响室的参数要求,对混响室模型的设计进行了研究,并确立了适用于短脉冲激励下的混响室的场均匀性分析指标;通过对比电场分布的均匀性,重点研究腔体形状和源搅拌方法对腔体内场分布的影响,采用连续10次移动激励源的方法可以将场分布标准差降低约0.4 dB。数值模拟结果表明:采用类似复杂腔的结构,在矩形腔的基础上引入若干复杂结构,可以有效地提高场分布的均匀性,有利于在腔内构造均匀的电磁环境;证明了连续移动激励源位置这一源搅拌方法的可行性,通过该方法可以有效地提高场分布的均匀性。