如何获取定义频段内的所有fft箱数量? [英] How do i get all the numbers of fft bins in a defined frequency band?

问题描述

我使用matlab软件.对我的问题. 我有一个音频信号，正在对其上应用STFT.我分段 我的信号y(audio signal)中的(46 ms, specifially chosen)，并在其上使用了FFT.然后我转到下一个片段，直到音频信号结束.

I use the matlab software. To my question. I have a audio signal, on which i am applying a STFT. I take a segment (46 ms, specifially chosen) out of my signal y(audio signal) and use a FFT on it. Then i go to the next segment, until to end of my audio signal.

我的WAV文件长10.8526秒.如果我的采样频率为 44100Hz，这意味着我的y是10.8526*fs = 478599.66 在工作区中显示为478 6000 x2 double.

My WAV-File is 10.8526 seconds long. If I have a sample frequency of 44100Hz, this means my y is 10.8526*fs = 478599.66 which is shown in the workspace as 478 6000 x2 double.

我的fft的长度是2048.我的信号在[0 300]，mfb [301 5000]和hfb [5001 22050(fs/2)]较低频段下有所区别.

The length of my fft is 2048. My signal are differentiated under lower frequency band [0 300], mfb [301 5000] and hfb [5001 22050(fs/2)].

这些频段仅是示例，并非实际的matlab代码. Basicall我想要的(或我想做的)是获取定义频段中箱的值并对其进行算术平均值.

The bands are just an example and not the actual matlab code. Basicall what i want (or what I am trying to do), is to get the values of my bins in the defined frequency band and do a arithmetic mean on it.

我选择46毫秒是因为，我希望它与fft长度一样长，或者几乎与fft一样长. (It is not exact).Afterwards，我想尝试绘制它，但是现在这并不重要.任何帮助表示赞赏.

I chose 46 ms because, I want it as long as the fft length, or nearly as long as the fft. (It is not exact).Afterwards, I want to try plotting it, but that is not important right now. Any help is appreciated.

推荐答案

在大小为n的向量中进行时域信号的傅立叶变换，将返回在频率域中相同信号的大小为n的另一个向量.

Fourier transform of a signal in time domain in a vector of size n will return another vector of size n of same signal but in frequency domain.

频率域将从0(直流偏移)到您的采样频率.但是您将只能使用其中的一半.下半部分将具有相同的值，但会被镜像.

Frequency domain will be from 0 (dc offset) to your sampling frequency. But you will only be able to use half of that. Second half would have same values but mirrored.

您可以使用以下方法获得每个有用仓的中心频率:

You can obtain the center frequency of each useful bin with:

f = Fs*(0:(n/2))/n;

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