SOUND TRANSMISSION LAW USING THE MASS LAW

SOUND TRANSMISSION LAW USING THE MASS LAW

          %% SOUND TRANSMISSION LAW USING THE MASS LAW %%
% C J NAIFY 2010, TRANSMISSION LOSS AND DYNAMIC RESPONSE OF MEMBRANE TYPE LOCALLY RESONANT ACOUSTIC METAMATERIALS %
% EQUATION NO 3, PAPER 2 BY LF %
clc;
clear all;

freq = linspace(100, 2000, 1000);
omega = 2*pi*freq;

% Properties of memebrane
% Method 1
rho_m = 1200; % Density of the membrane
thick_mem = 0.0762* (10^-3); % Thickness of the membrane in metre
r_mem = (29/2)*(10^-3);

%rho_s = rho_m*thick_mem; % Surface density of the membrane = (density * thickness) in Kg/(m^3)

% Method 2

mass_eqvt = 0.16*(10^-3); Area_mem = pi* (r_mem^2);
rho_s = mass_eqvt/Area_mem; 


% Properties of air
rho_0 = 1.200; % density of membrane
c = 343; % speed of sound in air

TL = 20*log(omega*rho_s/(2*rho_0*c));

figure(1)
plot(freq,TL); 

set(gca, 'XScale', 'log')
grid on
title('Sound Transmission loss')
xlabel('Frequency, in Hz')
ylabel('STL, dB')