課程設(shè)計-基于matlab的語音信號的時、頻域分析設(shè)計

1、<p><b>　　摘 要</b></p><p>　　用MATLAB對于語音信號進行分析和處理，采集語音信號后，在MATLAB軟件平臺進行頻譜分析；并對所采集的語音信號加入干擾噪聲，對加入噪聲的信號進行頻譜分析，設(shè)計合適的濾波器濾除噪聲，恢復(fù)原信號。本次設(shè)計介紹了基于MATLAB的對語音信號的采集，處理及濾波器的設(shè)計，并使之實現(xiàn)的過程。</p><p>

2、　　關(guān)鍵詞：MATLAB;語音信號；濾波器；加噪；除噪</p><p><b>　　目 錄</b></p><p><b>　　摘要1</b></p><p><b>　　1 設(shè)計原理1</b></p><p>　　1.1 理論原理1</p><p

3、>　　1.1.1采樣頻率1</p><p>　　1.1.2采樣位數(shù)1</p><p>　　1.1.3采樣定理1</p><p>　　1.1.4時域信號的FFT分析2</p><p>　　1.1.5數(shù)字信號的濾波器原理和方法2</p><p>　　1.1.6 各種不同類型濾波器的性能比較3</p

4、><p>　　1.1.7離散傅立葉變換3</p><p>　　2 信號采集及讀取4</p><p>　　3 構(gòu)造受干擾信號并對其進行FFT頻譜分析........................…...6</p><p>　　4 數(shù)字濾波器設(shè)計8</p><p>　　4.1 用窗函數(shù)法設(shè)計IIR帶通濾波器8&

5、lt;/p><p>　　4.2 用窗函數(shù)法設(shè)計FIR低通濾波器10</p><p><b>　　5信號處理12</b></p><p>　　5.1 IIR帶通濾波12</p><p>　　5.2 FIR低通濾波14</p><p><b>　　6心得體會16</b>&l

6、t;/p><p>　　7 參考文獻：16</p><p><b>　　1設(shè)計原理</b></p><p><b>　　1.1 理論原理</b></p><p>　　1.1.1采樣頻率</p><p>　　也稱為采樣速度或者采樣率，定義了每秒從連續(xù)信號中提取并組成離散信號的采樣

7、個數(shù)，它用赫茲（Hz）來表示。采樣頻率只能用于周期性采樣的采樣器，對于非周期性采樣的采樣器沒有規(guī)則限制。通俗的講采樣頻率是指計算機每秒鐘采集多少個聲音樣本，是描述聲音文件的音質(zhì)、音調(diào)，衡量聲卡、聲音文件的質(zhì)量標準。采樣頻率越高，即采樣的間隔時間越短，則在單位時間內(nèi)計算機得到的聲音樣本數(shù)據(jù)就越多，對聲音波形的表示也越精確。</p><p><b>　　1.1.2采樣位數(shù)</b></p&g

8、t;<p>　　即采樣值或取樣值，用來衡量聲音波動變化的參數(shù)，是指聲卡在采集和播放聲音文件時所使用數(shù)字聲音信號的二進制位數(shù)。</p><p><b>　　1.1.3采樣定理</b></p><p>　　在進行模擬/數(shù)字信號的轉(zhuǎn)換過程中，當采樣頻率fs.max大于信號中最高頻率fmax的2倍時(fs.max>=2fmax)，采樣之后的數(shù)字信號完整地保

9、留了原始信號中的信息，一般實際應(yīng)用中保證采樣頻率為信號最高頻率的5～10倍；采樣定理又稱奈奎斯特定理。</p><p>　　1.1.4時域信號的FFT分析</p><p>　　信號的頻譜分析就是計算信號的傅立葉變換。連續(xù)信號與系統(tǒng)的傅立葉分析顯然不便于用計算機進行計算，使其應(yīng)用受到限制。而FFT是一種時域和頻域均離散化的變換，適合數(shù)值運算，成為用計算機分析離散信號和系統(tǒng)的有力工具。對連續(xù)信

10、號和系統(tǒng)，可以通過時域采樣，應(yīng)用DFT進行近似譜分析。</p><p>　　1.1.5數(shù)字信號的濾波器原理和方法</p><p>　　IIR數(shù)字濾波器系統(tǒng)函數(shù)：</p><p>　　H(z)=··············

11、3;·（1.1）</p><p>　　其中H(z)稱為N階IIR數(shù)字濾波器系統(tǒng)函數(shù)。IIR濾波器設(shè)計方法有間接和直接法，間接法是借助于模擬濾波器的設(shè)計方法進行的。其步驟是：先設(shè)計過度模擬濾波器得到系統(tǒng)函數(shù)Ha(s)，然后將Ha（s）按某種方法轉(zhuǎn)換成數(shù)字濾波器的系統(tǒng)函數(shù)H(z)。</p><p>　　利用有限脈沖響應(yīng)(FIR)設(shè)計濾波器。有限脈沖響應(yīng)濾波器在保證幅度特性滿足技術(shù)要求

12、的同時，很容易做到有嚴格的線性相位特性。用N表示FIR濾波器單位脈沖響應(yīng)h(n)的長度，其系統(tǒng)函數(shù)H（z）為</p><p>　　··················（1.2）</p><p>　　H（z）是z-

13、1的N-1次多項式，它在z平面上有N-1個零點，在原點z=0處有一個N-1重極點。因此，H(z)永遠穩(wěn)定。穩(wěn)定和線性相位是FIR濾波器最突出的優(yōu)點。</p><p>　　1.1.6 各種不同類型濾波器的性能比較</p><p>　　巴特沃斯濾波器具有單調(diào)下降的幅頻特性；切比雪夫濾波器的幅頻特性在通帶或阻帶有波紋特性，可以提高選擇性；貝塞爾濾波器通帶內(nèi)有較好的線性相位特性；橢圓濾波器的選擇性

14、相對前三種是最好的，但通帶和阻帶內(nèi)均呈現(xiàn)等波紋幅頻特性，線性特性的非線性稍重。</p><p>　　IIR數(shù)字濾波器最大的優(yōu)點是給定一組指標時，它的階數(shù)要比相同組的FIR濾波器低得多。IIR數(shù)字濾波器的設(shè)計方法是利用模擬濾波器成熟的理論及設(shè)計圖進行的，因而保留了一些典型模擬濾波器優(yōu)良的幅度特性。但設(shè)計中只考慮了幅度特性，沒考慮相位特性，所設(shè)計的濾波器一般是某種確定的非線性相位特性。為了得到線性相位特性，對IIR濾

15、波器必須另外增加相位校正網(wǎng)絡(luò)。FIR濾波器在保證幅度特性滿足技術(shù)要求的同時，很容易做到有嚴格的線性相位特性。穩(wěn)定和線性相位是FIR濾波器最突出的優(yōu)點。</p><p>　　1.1.7離散傅立葉變換</p><p><b>　　1.3</b></p><p>　　其中,N為DFT變換的區(qū)間長度。</p><p>　　2

16、信號采集及讀取</p><p>　　用錄音工具錄一段自己的聲音，轉(zhuǎn)化為wav格式的文件，然后保存到MATLAB的文件夾下的work文件夾中。在MATLAB軟件平臺下，利用wavread函數(shù)對語音信號進行采樣，記住采樣頻率和采樣點數(shù)。</p><p>　　Wavread函數(shù)調(diào)用格式：</p><p>　　y=wavread(file),讀取file所規(guī)定的wav文件，

17、返回采樣值放在向量y中。</p><p>　　[y,fs,nbits]=wavread(‘1.wav’)；把語音信號進行載MATLAB仿真軟件平臺中，采樣值放在向量y中，fs表示采樣頻率（hz），nbits表示采樣位數(shù)。</p><p>　　sound（y,fs,nbits）；回放語音信號</p><p>　　N=length(y)；求出語音信號的長度</p&

18、gt;<p>　　Y=fft(y,N)；傅立葉變換</p><p>　　調(diào)用函數(shù)y為被變換的時域系列向量，N是DFT變換區(qū)間長度，當N大于y的長度時，fft函數(shù)自動在y后面補零，函數(shù)返回y的N點DFT變換結(jié)果向量Y。當N小于y的長度時，fft函數(shù)計算y的前面N個元素構(gòu)成的N點DFT，忽略y后面的元素。首先畫出語音信號的時域波形，然后對語音信號進行頻譜分析。在MATLAB中利用fft對新號進行快速傅立

19、葉變換，得到信號的頻譜特性。</p><p>　　subplot(2,1,1);plot(y);title(‘原始信號波形’);</p><p>　　subplot(2,1,2);plot(abs(Y));title(‘原始信號頻譜’)；</p><p><b>　　程序如下：</b></p><p>　　[y,fs,n

20、bits]=wavread('1.wav');</p><p>　　sound(y,fs,nbits);</p><p>　　N=length(y);</p><p>　　Y=fft(y,N);</p><p>　　subplot(2,1,1);</p><p><b>　　plot(y);&

21、lt;/b></p><p>　　title('原始信號波形');xlabel('時間');ylabel('幅度');</p><p>　　subplot(2,1,2);</p><p>　　plot(abs(Y));</p><p>　　title('原始信號頻譜');x

22、label('時間');ylabel('幅度');</p><p><b>　　程序結(jié)果如下圖：</b></p><p><b>　　程序如下：</b></p><p>　　[y,fs,nbits]=wavread ('1.wav');</p><p>

23、;　　N = length (y) ; %求出語音信號的長度</p><p>　　noise=0.2*randn(N,1); %隨機函數(shù)產(chǎn)生噪聲</p><p>　　Si=y+noise; %語音信號加入噪聲 </p><p>　　sound(Si);</p>

24、<p>　　subplot(2,1,1);</p><p><b>　　plot(Si);</b></p><p>　　title('加噪語音信號的時域波形');xlabel('時間');ylabel('幅度');</p><p>　　S=fft(Si);

25、 %傅里葉變換</p><p>　　subplot(2,1,2);</p><p>　　plot(abs(S)); </p><p>　　title('加噪語音信號的頻域波形'); xlabel('時間');ylabel('幅度');</p><p><b>　　

26、程序結(jié)果如下圖：</b></p><p><b>　　4 數(shù)字濾波器設(shè)計</b></p><p>　　4.1 用窗函數(shù)法設(shè)計IIR帶通濾波器</p><p><b>　　程序如下：</b></p><p>　　wp=0.2*pi; ws=0.3*pi; %性能指標</p>

27、;<p>　　wdelta=ws-wp; %過渡帶寬度</p><p>　　M=ceil(3.32*pi/wdelta); %濾波器長度，朝正無窮方向舍入</p><p>　　N=2*M+1; %窗口長度</p><p>　　wc=(ws+wp)/2; %截止頻率</p>

28、<p>　　win=hamming(N); %因為衰減不小于50dB，所以選擇海明窗，這里得到海明窗的時域響應(yīng)</p><p>　　b=fir1(N-1,wc/pi,win);</p><p><b>　　n=0:1:N;</b></p><p>　　[hi t]=impz(b,1,n);%得到脈沖響應(yīng)</p&

29、gt;<p>　　[hf w]=freqz(b,1,512); %得到頻率響應(yīng)</p><p>　　subplot(3,1,1); stem(n,hi);</p><p>　　xlabel('n'); ylabel('幅度'); title('脈沖響應(yīng)');</p><p>　　subplot(3,1,

30、2); plot(w/pi,20*log10(abs(hf)));</p><p>　　xlabel('頻率(Hz)'); ylabel('幅度(dB)');</p><p>　　title('頻率響應(yīng)');</p><p>　　subplot(3,1,3); plot(w/pi,180/pi*unwrap(angle

31、(hf)));</p><p>　　xlabel('頻率(Hz)'); ylabel('相位(degrees)');</p><p>　　title('頻率響應(yīng)');</p><p><b>　　程序結(jié)果如下圖：</b></p><p>　　4.2 用窗函數(shù)法設(shè)計FIR低通

32、濾波器</p><p><b>　　程序如下：</b></p><p><b>　　Ft=8000;</b></p><p><b>　　Fp=1000;</b></p><p><b>　　Fs=1200;</b></p><p&

33、gt;　　wp=2*Fp/Ft;</p><p>　　ws=2*Fs/Ft;</p><p><b>　　rp=1;</b></p><p><b>　　rs=50;</b></p><p>　　p=1-10.^(-rp/20);</p><p>　　s=10.^(-rs/2

34、0);</p><p>　　fpts=[wp,ws];</p><p>　　mag=[1,0];</p><p>　　dev=[p,s];</p><p>　　[n21,wn21,beta,ftype]=kaiserord(fpts,mag,dev);</p><p>　　b21=fir1(n21,wn21,kaise

35、r(n21+1,beta));</p><p>　　[h,w]=freqz(b21,1);</p><p>　　plot(w/pi,abs(h));</p><p>　　title('FIR低通濾波器');</p><p><b>　　grid;</b></p><p><b

36、>　　其程序結(jié)果如下圖：</b></p><p><b>　　5信號處理</b></p><p>　　用設(shè)計好的數(shù)字濾波器對含噪聲的語音信號進行濾波，在MATLAB中FIR濾波器利用函數(shù)fftfilt對信號進行濾波，IIR濾波器利用函數(shù)filter對信號進行濾波，在一個窗口同時畫出濾波前后的波形及頻譜如下圖。</p><p>

37、　　5.1 IIR帶通濾波</p><p><b>　　程序如下：</b></p><p>　　[y,fs,nbits]=wavread('1.wav');</p><p>　　N=length(y);</p><p>　　Noise=0.2*randn(N,1);</p><p>

38、;　　Si=y+Noise; %語音信號加入噪聲 </p><p>　　nn=0:1:50;</p><p>　　y=filter(b,1,Si);</p><p>　　subplot(2,1,1); stem(Si);</p><p>　　xlabel('n'); ylabel('幅度'

39、;);</p><p>　　title('濾波前信號頻譜'); axis([0 50 -2 2]);</p><p>　　subplot(2,1,2); stem(out);</p><p>　　xlabel('n'); ylabel('幅度');</p><p>　　title('濾波

40、后信號頻譜'); axis([0 50 -1 1]);</p><p><b>　　sound(y);</b></p><p><b>　　程序結(jié)果如下圖：</b></p><p>　　5.2 FIR低通濾波</p><p><b>　　程序如下：</b></p&

41、gt;<p>　　[y,fs,nbits]=wavread('1.wav');</p><p>　　N = length (y) ; </p><p>　　noise=0.2*randn(N,1); </p><p>　　Si=y+noise; </p><p>　

42、　S=fft(Si);</p><p>　　z21=fftfilt(b21,Si);</p><p>　　sound(z21);</p><p>　　m21=fft(z21);</p><p>　　subplot(2,2,1);</p><p>　　plot(abs(S),'g');</p>

43、<p>　　title('濾波前信號的頻譜');xlabel('時間');ylabel('幅度');</p><p><b>　　grid;</b></p><p>　　subplot(2,2,2);</p><p>　　plot(abs(m21),'r');<

44、/p><p>　　title('濾波后信號頻譜');xlabel('時間');ylabel('幅度');</p><p><b>　　grid;</b></p><p>　　subplot(2,2,3);</p><p><b>　　plot(S);</b>

45、;</p><p>　　title('濾波前信號波形');xlabel('時間');ylabel('幅度');</p><p><b>　　grid;</b></p><p>　　subplot(2,2,4);</p><p>　　plot(z21);</p>

46、<p>　　title('濾波后信號波形');xlabel('時間');ylabel('幅度');</p><p><b>　　grid;</b></p><p><b>　　程序結(jié)果如下圖：</b></p><p><b>　　6心得體會</b&

47、gt;</p><p>　　通過這次課程設(shè)計，我學到了很多東西。進一步加深了對MATLAB的了解。在設(shè)計的過程中我遇到了不少的問題，比如剛開始要處理的是WAV格式的語音信號，可是我發(fā)現(xiàn)不是所有的WAV文件都可以用WAVREAD函數(shù)讀取，通過軟件轉(zhuǎn)化了才可以使用。在編寫程序的時候遇到了很多錯誤，最后經(jīng)過查找一些資料和自己的理解都一一糾正了?？偟膩碚f，通過這次的課程設(shè)計我對語音信號有的更多的認識，對數(shù)字信號處理的知識

48、有了更多的理解，鍛煉了我的理論與實際相結(jié)合的能力，并且熟練的應(yīng)用MATLAB也加深了我對課程的理解。這次設(shè)計使我更深刻的了解MATLAB的使用方法，同時我相信，進一步加強對MATLAB的學習對我今后的學習將會起到很大的幫助。</p><p><b>　　7 參考文獻：</b></p><p>　　高西全，丁玉美編著?！稊?shù)字信號處理》西安，西安電子科技大學出版社，200

49、8</p><p>　　鄭君里等主編，《信號與系統(tǒng)》，北京，高等教育出版社。2000</p><p>　　陳懷琛等編著，《MATLAB及在電子信息課中的應(yīng)用》，北京，電子工業(yè)出版社，2002</p><p>　　g an employment tribunal claim</p><p>　　Employment tribunals sort

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60、ienced adviser, for example, at a Citizens Advice Bureau.  To find your nearest CAB, including those that give advice by e-mail, click on nearest CAB.</p><p>　　For more information about making a c

61、laim to an employment tribunal, see Employment tribunals.</p><p>　　The (lack of) air up there </p><p>　　Watch mCayman Islands-based Webb, the head of Fifa's anti-racism taskforce, is in

62、 London for the Football Association's 150th anniversary celebrations and will attend City's Premier League match at Chelsea on Sunday.</p><p>　　"I am going to be at the match tomorrow and I hav

63、e asked to meet Yaya Toure," he told BBC Sport.</p><p>　　"For me it's about how he felt and I would like to speak to him first to find out what his experience was."</p><p>　　U

64、efa has opened disciplinary proceedings against CSKA for the "racist behaviour of their fans" during City's 2-1 win.</p><p>　　Michel Platini, president of European football's

65、 governing body, has also ordered an immediate investigation into the referee's actions.</p><p>　　CSKA said they were "surprised and disappointed" by Toure's complaint. In a statement the R

66、ussian side added: "We found no racist insults from fans of CSKA."</p><p>　　Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became

67、the appearance of the same day; May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something

68、, or write something. Twenty years of life trajectory deeply shallow, suddenly feel something, do it.</p><p>　　一字開頭的年齡已經(jīng)到了尾聲。或許是愧疚于自己似乎把轉(zhuǎn)瞬即逝的很多個不同的日子過成了同一天的樣子；或許是追溯過去，對自己那些近乎偏執(zhí)的怪異信念的醒悟，這些天以來，思緒一直很凌亂，在腦海中不斷糾纏

69、?？傆X得自己自己似乎應(yīng)該去做點什么，或者寫點什么。二十年的人生軌跡深深淺淺，突然就感覺到有些事情，非做不可了。</p><p>　　The end of our life, and can meet many things really do?</p><p>　　而窮盡我們的一生，又能遇到多少事情是真正地非做不可？</p><p>　　During my chil

70、dhood, think lucky money and new clothes are necessary for New Year, but as the advance of the age, will be more and more found that those things are optional; Junior high school, thought to have a crush on just means th

71、at the real growth, but over the past three years later, his writing of alumni in peace, suddenly found that isn't really grow up, it seems is not so important; Then in high school, think don't want to give vent

72、to out your inner voice can be in the high school chil</p><p>　　童年時，覺得壓歲錢和新衣服是過年必備，但是隨著年齡的推進，會越來越發(fā)現(xiàn)，那些東西根本就可有可無；初中時，以為要有一場暗戀才意味著真正的成長，但三年過去后，自己心平氣和的寫同學錄的時候，突然就發(fā)現(xiàn)是不是真正的成長了，好像并沒有那么重要了；然后到了高中，覺得非要吐露出自己的心聲才能為高中生

73、涯里的懵懂情愫劃上一個句點，但畢業(yè)晚會的時候最終還是被梗塞在了咽喉，后來再次站在他曾經(jīng)揮汗如雨的球場，看著他投過籃球的球框時，突然間發(fā)現(xiàn)自己已經(jīng)想不起他的容顏。</p><p>　　Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time.

74、</p><p>　　原來，這個世界上，對某個事件能產(chǎn)生化學反應(yīng)的，除了非做不可的堅決，還有，時間。</p><p>　　A person's time, your ideas are always special to clear. Want, want, line is clear, as if nothing could shake his. Also once seemed

75、 to be determined to do something, but more often is he backed out at last. Dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. Those who do, j

76、ust green years oneself give oneself an arm injection, or is a self-righteous spiritual.</p><p>　　一個人的時候，自己的想法總是特別地清晰。想要的，不想要的，界限明確，好像沒有什么可以撼動自己。也曾經(jīng)好像已經(jīng)下定了決心去做某件事，但更多的時候是最后又打起了退堂鼓。嫌惡過自己的怯懦，最終卻發(fā)現(xiàn)有很多緣分，有很多錯過，好

77、像冥冥之中真的已經(jīng)注定。那些曾經(jīng)所謂的非做不可，只是青蔥年華里自己給自己注射的一支強心劑，或者說，是自以為是的精神寄托罷了。</p><p>　　At the moment, the sky is dark, the air is fresh factor after just rained. Suddenly thought of blue plaid shirt; Those were broken into

78、 various shapes of stationery; From the corner at the beginning of deep friendship; Have declared the end of the encounter that haven't start planning... Those years, those days of do, finally, like youth, will end i

79、n our life.</p><p>　　此刻，天空是陰暗的，空氣里有著剛下過雨之后的清新因子。突然想到那件藍格子襯衫；那些被折成各種各樣形狀的信紙；那段從街角深巷伊始的友誼；還有那場還沒有開始就宣告了終結(jié)的邂逅計劃……那些年那些天的非做不可，終于和青春一樣，都將在我們的人生中謝幕。</p><p>　　Baumgartner the disappointing news: Missio

80、n aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm -- winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule

81、 attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher th

82、an the cruising al</p><p>　　The supersonic descent could happen as early as Sunda.</p><p>　　The weatheThe balloon will slowly drift to the edge of space at 120,000 feet (</p><p>　　T

83、hen, I would assume, he will slowly step out onto something resembling an Olympic diving platform.</p><p>　　Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not t

84、oo hard. Still, he'll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end. </p><p>　　Skydiver preps for t

85、he big jump</p><p>　　When he jumps, he is expected to reach the speed of sound -- 690 mph (1,110 kph) -- in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches th

86、e more dense air closer to Earth. But this will not be enough to stop him completely.</p><p>　　If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him d

87、own. His team hopes it's not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).</p><p>　　In order to deploy this chut

88、e successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.</p><p>　　Even if everything goes as planned,

89、 it won't. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).</p><p>　　cause there</p&g