MATLAB信号分析.ppt

Dr WangZhengsheng - Lecture Notes * Lecture 4 MATLAB信号分析（Sound Analysis） Dr WangZhengsheng - Lecture Notes * Lecture 4 Matlab语音分析 基本要求 （1）掌握语音文件的创建与控制，以及语音文件的基本操作； （2）熟练掌握录制语音基本的命令和控制； （3）初步掌握用傅里叶变换来表现信号的波形和频谱。 （4）掌握坐标轴的控制和图形标注命令及其用法。 Dr WangZhengsheng - Lecture Notes * Lecture 4 Matlab语音分析 1.语音录制函数 wavrecord Record sound using Windows audio input device. wavrecord will be removed in a future release. Use AUDIORECORDER instead. 命令格式: Y = wavrecord(N,FS,CH) records N audio samples at FS Hertz from CH number of input channels from the Windows WAVE audio device. Standard audio rates are 8000, 11025, 22050, and 44100 Hz. CH can be 1 or 2 (mono or stereo). Samples are returned in a matrix of size N-by-CH. If not specified, FS=11025 Hz, and CH=1. Dr WangZhengsheng - Lecture Notes * Lecture 4 Matlab语音分析 Y=wavrecord(..., DTYPE) uses the data type specified by the string DTYPE to record the sound. The string values for DTYPE are listed in the following table along with corresponding bits per sample and acceptable data ranges for Y. DTYPE Bits/sample Ys Data range -------- ----------- --------------------- double 16 -1.0 = Y +1.0 single 16 -1.0 = Y +1.0 int16 16 -32768 = Y = +32767 uint8 8 0 = Y = 255 Dr WangZhengsheng - Lecture Notes * Lecture 4 Matlab语音分析 Example: Record and play back 5 seconds of 16-bit audio sampled at 11.025 kHz. Fs = 11025; y = wavrecord(5*Fs, Fs, int16); wavplay(y, Fs); Dr WangZhengsheng - Lecture Notes * Lecture 4 Matlab语音分析 2.语音文件生成函数 wavwrite Write Microsoft WAVE (.wav) sound file. wavwrite(Y,FS,NBITS,WAVEFILE) writes data Y to a Windows WAVE file specified by the file name WAVEFILE, with a sample rate of FS Hz and with NBITS number of bits. NBITS must be 8, 16, 24, or 32. Stereo data should be specified as a matrix with two columns. 命令格式: wavwrite(Y,FS,NBITS,WAVEFILE