Speech signal processing - concept (I): time spectrum (horizontal axis: time; vertical axis: amplitude), spectrum (horizontal axis: frequency; vertical axis: amplitude) -- Fourier transform -- > time

One 、 Time domain 、 frequency domain

Time domain and frequency domain are the basic properties of signals , The different angles used to analyze signals are called domains , Generally speaking , The representation of time domain is more visual and intuitive , Frequency domain analysis is more concise , Analyzing problems is more profound and convenient . at present , The trend of signal analysis is from time domain to frequency domain . However , They are interconnected , Be short of one cannot , Complement each other .

Time domain and frequency domain of signal

• The time domain is the time domain , The argument is time , That is, the horizontal axis is time , The vertical axis is the change of signal . The dynamic signal is a function that describes the value of the signal at different times . Time domain analysis is to represent the relationship between dynamic signals with time axis as coordinates .
• Frequency domain is frequency domain , The independent variable is frequency , That is, the horizontal axis is the frequency , The vertical axis is the amplitude of the frequency signal , That is commonly known as spectrum diagram . The spectrum diagram describes the frequency structure of the signal and the relationship between the frequency and the amplitude of the frequency signal . The frequency domain is a complex frequency domain expression obtained by Fourier transformation of the time domain waveform expression , The waveform drawn is the spectrum diagram .

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Reference material ：
Audio features （2）： Time domain graph 、 spectrum 、 Spectrogram （ Time spectrum diagram ）
What is the time domain and frequency domain of a signal ？