% vibrato.m  Create vibrato sound
t = 0:1/8000:2;
% y = cos(2*pi*t);  % pure tone 1 Hz
% Create 100 Hz signal with frequency that changes up and down as it goes.
y = cos(2 * pi * 100 * (1 + 0.5 * sin(2*pi*10*t)).*t);  % Try sin(2*pi*t) for vibrato too.
y = 0.2*y;   % Sound is too loud without scaling.
sound(y)