音频信息处理技术合编.ppt

音频信息处理技术 1 Basics of Digtial Audio 声学基础知识 2 Digitization of Sound 音频信号数字化 3 Audio signal compression coding音频信号压缩编码 4 Coding standard of Speech compression 语音压缩编码标准 5 Multimedia audio signal file format多媒体音频信号文件格式 made by fangshuailijian @8#319 1 Basics of Digtial Audio 声学基础知识 1.1 Audio signal characteristics音频信号特征 1、The time domain characteristics of voice signal声音信号的时域特征 This feature suggests people hear the voice of the process from production to the end of the.该特征说明人们听到的声音从产生到结束的过程。 This process can be divided into three stages: initiation, stable and end.这个过程大致可分为三个阶段：起始、稳定和结束。 2、The frequency characteristics of sound signal声音信号的频域特征 The frequency of the acoustic wave声波频率 20Hz~20kHz （Hertz） Sound pressure:The sound intensity of feeling 1kHz~2＊10-5Pa 1.2 The auditory characteristics 1、Loudness：The human ear to sound intensity of feeling。 2、Masking effect： A voice will influence the existence of people hearing ability of other sounds, make a sound in the auditory masking another sound。 2 音频信号数字化 The process of digital audio signal is analog audio signal into a discrete sequence of a finite representation of numbers, digital audio sequence。It includes Sampling, quantization, coding 1、What is the sampling In the process of continuous signal discrete time general, sampling is generally carried out according to the uniform time interval。 2、What is the quantitative Quantization is each sampled values are discretized in amplitude。 3、What is the code The encoding process is indicated by binary numbers