Change Impulse in a 3D Wave Simulation.

Hi! I'm working on a 3D wave propagation project and I've designed an impulse response, but I would like to change it to an audio file source. Problem is, I'm having a hard time conceiving how to do so.

% Desired Impluse
[impulse, fs] = audioread('snare.wav');

% Current Method
u = zeros(nx+1, ny+1, nz+1);
uNext = zeros(nx+1, ny+1, nz+1);
u(floor(nx/2), floor(ny/2), floor(nz/2)) = 1; % Impulse
u((3:9), (3:9), (3:9)) = hann3D(7); % Displacement
uPrev = u; 

% 3D Wave Equation
uNext(x,y,z) = (2 * u(x,y,z) - uPrev(x,y,z) ...
        + lambdaSq * (u(x+1,y,z) + u(x,y+1,z) + u(x,y,z+1)...
        - 6*u(x,y,z) + u(x-1,y,z) + u(x,y-1,z) + u(x,y,z-1)));

Please let me know if you need the full code to understand what I'm attempting to do.