1、收稿日期:2003-10-21作者簡介:鄭長義(1949-,男,吉林東豐人,現(xiàn)任吉林師范大學(xué)信息技術(shù)學(xué)院講師.2003年11月吉林師范大學(xué)學(xué)報(自然科學(xué)版.4第4期Journal of Jilin Normal University (Natural Science Edition Nov.音頻頻譜分析儀的設(shè)計鄭長義(吉林師范大學(xué)信息技術(shù)學(xué)院,吉林四平136000摘要:文章介紹了用MA TLAB 的數(shù)據(jù)采集工具箱,采集音頻信號的方法,同時對采集到的音頻信號進(jìn)行波形顯示和頻譜分析.文中給出了具體的硬件和一個實用程序及其運行結(jié)果.關(guān)鍵詞:MA TLAB ;數(shù)據(jù)采集;音頻信號;頻譜分析中圖分類號:O

2、422.2文獻(xiàn)標(biāo)識碼:A 文章編號:1000-1840-(200304-0070-02音頻頻譜分析儀具有實際意義,如器樂標(biāo)準(zhǔn)音的標(biāo)定,聲樂的發(fā)聲校正,使用音頻頻譜儀會事半功倍.該音頻頻譜分析儀是用電腦中的聲卡通過傳聲器在MA TLAB6.5的數(shù)據(jù)采集工具DA TA ACQU ISITION TOOLBOX 把音頻信號輸入到電一組中的al (A 調(diào)的do (C 調(diào)的la =440Hz ,以它為標(biāo)準(zhǔn)求出其它各高音的頻率,如鋼琴中的小字一組的七個高音:cl dl el fl gl al bl 分別為:al =440Hz ,bl =al 3216=44031.1224625=493.88Hz ,gl

3、=al/216=440/1.1224625=392.00Hz ,fl =gl/216=392.00/1.1224625=349.23Hz ,el =fl/2112=349.23/1.0594631=329.63Hz ,dl =el/216=329.63/1.1224625=293.66Hz ,cl =dl/216=293.的命令窗口上.該分析儀的程序清單如下:function second ,voltage ,frequency ,magni 2tude =soundin (VoiceFrequencyFactor ,rate ;%this is a experiment that input

4、 is done using the sound card%2003,6,3;%Usage :second ,voltage ,frequency ,magnitude =soundin.%(VoiceFrequencyFactor ,rate %VoiceFrequencyFactor is set as 1/8and rate as8000,when the frequency is%below 40hz round measurement ;VoiceFrequen 2cyFactor as 1/200and rate as%44100hz ,when up 4khz%The comme

5、nts at command lines is active ,when the function is called.if nargin <2rate =8000;end ;if nargin <1VoiceFrequency =1/20;07end;ai=analoginput(winsound;addchannel(ai,1;ai.logtodiskmode=overwrite;ai.loggingmode=disk&memory;ai.triggertype=immediate;ai.samplerate=rate;actualrate=get(ai,sampler

6、ate;ai.samplespertrigger=VoiceFrequency3rate;% For zoom in x axes,that plot laterfs=actualrate; dt=1/fs;start(ai;data,time=getdata(ai;blocksize=VoiceFrequency3rate;%the default value is2205f,mag=daqdocfft(data,fs,blocksize;figure;subplot(2,1,1;plot(time,data;grid on;title(immediate trigger;xlabel(re

7、lative time%in second;ylabel(data in volts;second,voltage=ginput(5;pause;subplot(2,1,2;hold on;plot(f,mag;grid on;magnitude,frequency=ginput(5;ylabel(magnitude(db;title(frequency components of sound;xlabel(frequency(hz;delete(ai;clear ai;在MA TLAB窗口下,鍵入second,voltage, frequency,magnitude=soundin,即可分析

8、4KHz 以下的音頻頻率,如果分析4KHz以上的音頻頻率要給出函數(shù)的輸入?yún)?shù)VoiceFrequencyFactor 的值,如果它的分?jǐn)?shù)值很小,比如1/100,8KHz以下的波形能夠看得清楚,而rate的值,即采樣頻繁設(shè)為44100.當(dāng)按下回車鍵,波形出現(xiàn)在屏幕上,光標(biāo)帶上大十字,選擇你喜歡的幾個點,分別點擊鼠標(biāo)左鍵直到光標(biāo)的大十字去掉,然后在按任一鍵,頻譜圖即出現(xiàn)在波形圖的下面,同樣光標(biāo)也帶上大十字選擇你喜歡的幾個點,分別點擊鼠標(biāo)左鍵直到光標(biāo)的大十字去掉,這時返回到MA TLAB 命令窗口,即可看到各點的測量值.MA TLAB6.5是功能強大的軟件,在數(shù)據(jù)采集方面有專用的工具箱.這里介紹的利

9、用電腦的聲卡輸入信號,也可利用聲卡輸出信號.除此之外,數(shù)據(jù)采集工具箱還支持各式各樣數(shù)據(jù)采集卡.在儀表控制方面支持IEEE488HPIB V ISA 串口,TCPIP和UDP接口.參考文獻(xiàn)1伍湘濤.音樂知識與名曲賞析M.北京:航空工業(yè)出版社,1993,3.2車晴.電子系統(tǒng)仿真與MATLABM.北京:北京廣播學(xué)院出版社,2000,11.Design of Adio Spectrom AnalyzerZH EN G Chang2yi(College of Information Technology,Jilin Normal University,Siping Jilin136000,ChinaAbstract:In the paper,technique of acquisition a