Method to find the median/average of graph

I want to plot the median or average in graph. This is audio file in frequency domain and need to smoothen out the peak and converge them into two or three peaks as shown below. is there a specific code to do that?

Answer 1

[Image Analyst]

Try this:

% Initialization steps.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 15;

% read file into memory */
[wave, fs]=audioread('1.wav'); 
% sound(wave, fs); % see what it sounds like */
t=0:1/fs:(length(wave)-1)/fs; % and get sampling frequency */

subplot(3, 1, 1)
%plot(t,wave)
plot(t, wave, 'b-');
title('Wave File', 'FontSize', fontSize);
ylabel('Amplitude', 'FontSize', fontSize);
xlabel('Length (in seconds)', 'FontSize', fontSize);
grid on;

L = length(wave);
NFFT = 2^nextpow2(L); % Next power of 2 from length of y
Y = fft(wave,NFFT)/L;
f = fs/2*linspace(0,1,NFFT/2+1);

% Plot single-sided amplitude spectrum.
subplot(3, 1, 2);
y = 2*abs(Y(1:NFFT/2+1));
plot(f, y, 'b-');
title('Single-Sided Amplitude Spectrum of y(t)', 'FontSize', fontSize);
xlabel('Frequency (Hz)', 'FontSize', fontSize);
ylabel('|Y(f)|', 'FontSize', fontSize);
grid on;

subplot(3, 1, 3);
y = 2*abs(Y(1:NFFT/2+1));
plot(f, y, 'b-');
title('Single-Sided Amplitude Spectrum of y(t)', 'FontSize', fontSize);
xlabel('Frequency (Hz)', 'FontSize', fontSize);
ylabel('|Y(f)|', 'FontSize', fontSize);
grid on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
xlim([0, 400]);

% Smooth with a Savitzky Golay Filter
smoothy = sgolayfilt(y, 2, 101);
hold on;
plot(f, smoothy, 'r-', 'LineWidth', 2);

% Get the upper envelope
uppery = movmax(y,51);
% Smooth it out some
windowWidth = 31;
uppery = conv(uppery, ones(windowWidth, 1)/windowWidth, 'same');
plot(f, uppery, 'r-', 'LineWidth', 2);

[Harindu Kodithuwakku]

Thank you very much!

Answer 2

[Image Analyst]

Use the envelope() function, if you have the Signal Processing Toolbox. Or you can use sgolayfilt() or boundary(). Since it's so easy, you probably won't need help with that, but if you do, attach your data along with code to read it in.

[Harindu Kodithuwakku]

 The attached is is the code that I got to to plot the amplitude 
and also the audio file . I need to smoothen out the second graph which is FFT of the audio file