FFT - How to transform my amplitudes into dB
350 ビュー (過去 30 日間)
古いコメントを表示
Hello,
I have done a code to obtain the FFT of an audio recorded with Matlab. I'm getting my result in amplitude but I'd like to get it in dB in the frequency domain... Could someone please help me?
Here is my code and my curves:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1419398/image.png)
Thank you for your help.
0 件のコメント
採用された回答
Frantz Bouchereau
2024 年 12 月 10 日
編集済み: Gabriele Bunkheila
2024 年 12 月 10 日
Here is a popular MATLAB doc page that explains the relationship between FFT and true power spectra: Power Spectral Density Estimates Using FFT. Use this to scale the FFT to obtain true power values.
0 件のコメント
その他の回答 (1 件)
Diya Tulshan
2023 年 6 月 26 日
Hii Jacques,
I understand you want to plot the data in db.
Kindly look into the code given below, it should solve your problem:-
Fs = 16000; % Sampling rate (Hz)
Channels = 1; % Number of audio channels
bits = 16; % Number of bits per sample
r = audiorecorder(Fs, bits, Channels);
duration = 10;
disp('Recording started');
recordblocking(r, duration);
disp('Recording stopped');
X = getaudiodata(r);
N = length(X);
f = (0:N/2) * (Fs/N);
t = (0:N-1) / Fs;
subplot(2,1,1);
plot(t, X);
xlabel('Time (s)');
ylabel('Amplitude');
title('Time Domain Plot');
Y = fft(X, N);
Y = abs(Y(1:N/2+1));
fftResult_dB = 20 * log10(Y); % covert into dB
subplot(2,1,2);
plot(f, fftResult_dB);
xlabel('Frequency (Hz)');
ylabel('Amplitude (dB)');
title('Frequency Domain Plot');
xlim([0, Fs/2]);
grid on;
Hope this helps!
参考
カテゴリ
Help Center および File Exchange で Fourier Analysis and Filtering についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!