语音识别的MFCC算法研究

详细介绍了一种在语音识别中取得一定良好效果的Mel倒谱提取的改进算法。在语音识别系统中,MFCC参数是经常使用的特征参数之一。MFCC参数主要描述了表征声道特性的谱包络特征,而忽略了基音频率对它的影响。然而基音频率会影响MFCC参数对声道特性的准确描述,进一步影响语音识别系统的性能。提出了一种MFCC的改进参数,该参数并不直接对语音短时幅度谱进行提取,而是首先对幅度谱进行平滑,在谱包络的基础上计算MFCC参数,从而降低基音频率对其的影响。     

基于压缩感知观测序列的语音信号基音周期提取

语音信号的清浊音辨别及基音周期的提取是语音信号处理的重要组成部分。提出了一种基于压缩感知（CS）观测序列的语音基音周期提取方法,大大减少了基音周期提取的计算量。首先分析不同观测矩阵下观测序列的特征,选择了行阶梯矩阵作为所提方法的观测矩阵;然后对此观测矩阵下的观测序列做小波分解,对小波分解的低频系数采用自相关方法提取基音周期。仿真与分析表明,和传统方法比较,所提方法与传统方法基音检测准确度相当,且在语音含有高斯白噪声的条件下运行良好,但计算量仅约为传统方法的1/16。     

基于LPCC和能量熵的端点检测

为提高语音端点检测系统在低信噪比下检测的准确性,提出了一种基于倒谱特征和谱 熵的端点检测算法。首先,根据分析得到待测语音帧的倒谱特征量,然后计算该特征量分别 在 通过训练得到的语音和噪声的高斯混合模型下的似然概率,通过两者概率的比较作出有声无 声初判决;联合能量熵端点检测结果得到最终判决,最后通过Hangover机制最大限度的保护 了语音。实验结果表明,此方法改善了能量熵端点检测法在babble噪声下的劣势,且在不同 噪声环境下均优于G.729 Annex B的性能。     

一种新的语音二项式正弦脉冲激励方案

本文提出一种新的用于LPC语音编码器的BSP激励信号，即根据语音产生的原理，以一个幅度受到二项式调制的正弦波BSP（Binomial Sine Pulse)作为LPC激励源，该二项式反映了激励信号在一个基音周期内的变化趋势。本文同时推导了BSP激励参数的求取和改进方法。实验结果表明，在此基础上构造的BSP语音编解码器具有低复杂度、低时延的优点，同时编码速率在低至2．65kb/s时，具有较高的合成语音质量。     

基于TMS320VC5402的语音检测器

本文介绍的语音检测器以DSP芯片TMS320VC5402为核心，对短波电台接收到的信号进行分析和处理。数字语音信号采用串行输入／输出方式，语音检测算法则采用对语音信号进行降噪处理后，再进行短时平均幅度差和短时能量计算的方法。该语音检测器的电路简洁小巧，语音检测准确度高。     

利用频谱排序和筛选的突变噪声快速估计

针对最小值控制递归平均(Minima Controlled Recursive Averaging,MCRA)算法不能快速跟踪突变噪声的问题，提出了一种基于频谱排序和筛选的突变噪声快速估计方法。该方法在MCRA算法的基础上对带噪语音的功率谱进行排序，筛选出不含语音信号的频点来估计噪声的平均功率谱；当检测到噪声突变时，对当前的平滑参数和状态变量进行校正。仿真结果表明，该方法可以将突变噪声的跟踪时间缩短90%以上；用于语音降噪处理时，音质可以提升约0.4分。该方法具有一定的工程应用价值。     

单麦克风和双麦克风语音增强系统的研究

本文对采用减谱法和箱关法的语音增强系统进行了研究，系统的噪声为白噪声和普通机房噪声。减谱法采用单麦克风输入，试验中发现语音的分帧方法对消噪影响很大，通过比较得到了一种具有明显消噪效果的分帧方法，在相关法中采用双麦克风输入，对两个输入信号之间的时延差进行了补偿，在求维纳滤波器系数时，对信号谱进行统计平均，从而使消噪后的语音信号具有较好的自然度。在研究以上两种方法的基础上，我们提出了一种混合消噪系统，     

一种基于低比特率语音算法的芯片设计与分析

介绍了一种低比特率语音算法,它是在MBE编码算法的基础上,利用线性预测谱代替了MBE中的傅里叶变换谱对MBE编码算法进行了改进,从而在保持语音质量的情况下使比特率更低,达到2 kbit/s.同时阐述了基于该算法的系统芯片设计,并对该算法中的基音周期参数、V/U等参数的提取进行详细的推导分析.最后对本算法与常用的码激励线性预测编码(CELP)的算法进行比较,并分析其中的原因.     

机载环境下的语音端点检测

由于传统的语音端点检测方法仅以信号的短时能量、过零率等简单的单一特征作为判决特征参数,这些方法在实际应用中,很多都无法满足系统的需要。针对机载环境下的带噪语音进行研究,在传统方法的基础上作了两点改进:把短时能量和过零率结合为一个特征即短时能零积,并把其和短时自相关函数结合起来作为端点检测的特征参数。对于短时自相关的门限,不是利用传统的主副峰比值,而是利用达到副峰的时间间隔作为判决门限。通过对不同信噪比的机载环境下的带噪语音进行试验仿真,发现这种方法比单一的特征参数更有优越性,效果更明显。     

论嵌入式语音识别系统的研究与实现

在介绍了语音识别技术的基础上,根据语音识别系统的构成模型,实现基于嵌入式系统的语音识别系统。本系统采用了能量过零率双门限法进行语音文件端点检测,采用线性预测倒谱系数作为语音信号特征矢量,另外,基于非特定人的嵌入式系统要求,为了达到减少计算量和存储量的目的,在特征参数提取完成之后,利用矢量量化方法进行数据压缩。语音识别模型采用(DHMM)离散隐马尔可夫模型,利用Baum-Welth重估算法、前向后向算法、viterbi算法来完成语音模板的训练和语音识别的任务。     

Public Financial Expenditure——A Reflection of the Livelihood Improvement

In recent years.China's public finance put social construction high on the agenda and attaches more importance on livelihood insurance and improvement.The 2003-2007 public financial expenditure reflects a fact that the government isputting more emphasis on livelihood andissues concerning the people.     

Voices from the MPC and CPPCC

"Crucial for economic growth.energy utilization has its role in all economic sectors and every aspect of people's daily life.Now we are in dire need of a new profession,namely energy manager.We not only need to have passion and responsibility,but also a scientific approach to conserve energy and cut emissions.APpropriate legislation should be in place.and a special profession should be introduced to ensure the implementation of these laws and regulations."     

Slowdown Trade Surplus Growth

According to Ma Kai＇s economic planning report submitted to the NPC session on March 5th,（Ma Kai is the Minister in charge of the National Development and Reform Commission）,the government has listed the slowdown in trade surplus growth and the steady expansion of external investment as major tasks for 2008.     

Ouyang Riping： A Hero Besides Entrepreneur

A bout fifty years ago. a baby＇s cry broke the sky of quietness, in a small and beautiful town of Hunan province, which surroundcd by green hills and clear water. Though his .birth brought his family great happiness and hope just as any new life, nobody knew that the little boy would get great achievement when he grow up. even start his business oversea, and earn international honor. Let＇s share with you the entrepreneur Ouyang Riping＇s story, which may insights thcsc people who want to succeed and complete oneself in favorite condition or adversity rather leave things to so-called fate.     

Belarus, A Chinese Fort in Europe

＂In recent years, we＇ve found increasing interest from Chinese investors in the Belarus economy. Please let China know, Belarus is always ready to be a true friend to China. We have built a fort in Europe for China,＂ the President of Belarus, Alexander Lukashenko told Zhou Xiaochuan, President of the Bank of China, during his visit to the capital of Minsk, on January 8th, he expressed his high praise and firm confidence in the development of Sino-Belarusian relations.     

What＇s Behind Spring Festival？

Similar to what the Christmas Day means for the westerners,the Spring Festival is the most important celebration for Chinese people.This big event according to Chinese traditional lunar calendar relaxes and pleases the whole country as the happiest gathering time of the year.National-wide crusade for going back home,too-difficult-to-get train tickets,generous family-going-out shopping,Miaohui laundering,New Year Eve reunion dinner,visiting friends and relatives,watching annual TV gala......each piece of clue reminds us of the smell of Chinese Spring Festival.     

KEY WDRDS for Foreign Investment in China

FDI(Foreign Direct Investment),a component of a country's national financlal accounts,is investment of foreign assets into domestic structures,equipment,and organizations.It does not include foreign investment into the stock markets,concession and subcontract.FDI iS thought to be more useful to a country than investments in the equity of its companies because equity investments are potentially "hot money"which can leave at the first sign of trouble,whereas FDI is durable and generally useful whether things go well or badly.     

Brown＇s Blossom in Britain-China

The overall strategic relationship between U.K. and China is ＂better than ever＂, China- Britain relations have maintained good momentum, with increased high-level exchanges and the reinforcement of strategic mutual trust, with more room for growth in the future.     

Challenge and Opportunity Go Hand in Hand——What Global Economic Agitation Brings to the China's Economy?

Domino effects of the global finance agitation As the origin of the subprime crisis,US financial institutions lost USS45 billion last year,accounted for over half of the total US,EU & Japan loss.Since January 15th,Chtigroup released its financial statement of the 4th quarter,showing a net deficit of USS9.83 billion,which marked the hisoric high of its quarterly deficit.     

Consumption, New Protagonist in 2007 GDP

Not long ago, the National Bureau of Statistics released its 2007 Macro Economy Index. Social consumption retail sales reached RMB 8.9 billion, increased by 16.8 percent over the previous year, or 3.1 percentage points higher; the whole investment in social fixed assets was valued RMB 13.7 billion, a year-on-year increase of 24.8 percent, that is 0.9 percentage points higher; and trade surplus amounted to RMB 24.7 billion, rising by 47.7 percent compared with the same period last year, 26.3 percentage points falling over the increasing speed last year. According to preliminary estimates, GDP for the year was RMB 24.67 trillion, up by 11.4 percent from the previous year,