How to remove noise from a certain frequency using FFT

3 次查看（过去 30 天）

Shern Wei Lee 2020-9-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/596719-how-to-remove-noise-from-a-certain-frequency-using-fft

评论： Shern Wei Lee 2020-9-21

I would like to know how to remove noises at a certain frequency using only the code below. Don't worry I have attached the sound file in the above so you use it. The problem I am facing is that I do not know how to do to find the index for this array to help cancel out all the noise greater than 3500 Hz or in this case the freq = 3500. I have the question of the code in here as well.

clear;
close all;
clc;
[y, Fs] = audioread('unfiltered_sound.wav');
dt = 1/Fs;
N = length(y(:,1));
nu_Ny = 1/(2*dt);
nu = linspace(0, 2*nu_Ny, N); 
f = Fs*(0:(N/2))/N;
F = fft(y);
figure(1);
plot(nu, abs(F))
freq = 3500;
[~, ind] = min(abs(f-freq)); 
F_filtered = F;
F_filtered(ind:end-ind) = zeros(length([F_filtered(ind:end-ind)]),1);
%  
figure(2)
plot(nu, abs(F_filtered))
%   
y_filtered = ifft(F_filtered);
%  
audiowrite('filtered_sound.wav', y_filtered, Fs)

6 个评论
显示 4更早的评论隐藏 4更早的评论

Sindar 2020-9-21

what about compared to the original signal? Does it look like it is filtering the right area? If not, my first guess would be that 'f' and 'nu' are not consistent (or at least, not what you expect)

Shern Wei Lee 2020-9-21