Generating sound by multiplying the whole frequency spectrum

Hello everyone, I have analyzed an audio signal and found the fundamental frequency of a note and I multiply this frequency in order to generate other notes. But in a secondary level, I would like to multiply the whole frequency spectrum of the note, not just the fundamental ( to make a more complete sound).

%% _____________________________________________Audio Production
clear all
close all
clc
%___________________Load Audio Signal Analysis Outputs
 
load('SpecA1.mat')    %Frequency Spectrum after the audio analysis / replaced the fundamental frequency
%_________________________________________Ratio Inputs
 
A = input('Enter a new numerator for the ratio (must be a real, positive number): \A1->(1) \A3->(4) \A4->(3) \A5->(2) \n...');
B = input('Enter a new denominator for the ratio (must be a real, positive number): \A1->(1) \A3->(3) \A4->(2) \A5->(1) \n...');
 
F=A/B*SpecA1;         %multiplication of spectrum
 
%_____________Generating Damped Oscillation Sound Wave
 
Fs=44100;
f = linspace(1/Fs, 1000, 2^12);
x = zeros(Fs*4, 1);
delay = round(Fs/F);
 
b  = abs(firls(42, [0 10/delay 20/delay 1], [0 0 1 1]));
a  = [1 zeros(1, delay) -0.5 -0.5];
 
[H,W] = freqz(b, a, f, Fs);
Hf=20*log10(abs(H));
 
%___________Plotting Frequency Spectrum & Fundamentals
 
figure;
plot(W, Hf);
title('Spectrum Analysis of Artificial Note');
xlabel('Frequency (Hz)');
ylabel('Amplitude');
xlim([0 1000])
hold on
 
[pks, locs]=findpeaks(Hf, 'MinPeakProminence', 40, 'MinPeakDistance', F-10);
ylv = ylim;
plot([1;1]*W(locs), ylv(:)*ones(size(pks)))
text(W(locs(1)), pks(1)/2, sprintf('\\leftarrow %.1f Hz = Fundamental Frequency',W(locs(1))), 'HorizontalAlignment','left');
hold off
 
zi = rand(max(length(b),length(a))-1,1);
note = filter(b, a, x, zi);
 
%_________________________________Play Artificial Note
 
sound(note,Fs);
%______________________________________________________________End

I am not sure as to what modifications I have to make in order to make this multiplied spectrum be audible.

Thank you very much in advance!