Boeing 777-style CPDLC/ACARS chime

I couldn't find any clean Boeing 777-style CPDLC/ACARS chime on the web, so I tried making one with Matlab.  What I made is a 0.49-s 1150-Hz sinusoide followed by a 0.60-s 580-Hz sinusoid with some amplitude modulation.  This is pretty much a D-D with one octave separation.  I am not sure about the fidelity of the sound but it shouldn't be too bad.

acars.wav

For iPhone email notification:
new-mail.caf

A = 0.25;

T1 = 0.49;
T2 = 0.60;

Tr1 = 0.04;
Tr2 = 0.04;

f1 = 1150;
f2 = 580;

fs = 44100;

t1 = 0:1/fs:T1;
t2 = 0:1/fs:T2;

% base
y1 = A * sin(2*pi*f1*t1);
y2 = A * sin(2*pi*f2*t2);

% Envelope
k1 = 1:round(fs*Tr1);
k2 = round(fs*Tr1)+1:round(fs*T1);

y1(k1) = y1(k1) .* fliplr(sqrt(1-(k1/k1(end)).^2));
y1(k2) = y1(k2).* fliplr(k2-k2(1))/length(k2);

k1 = 1:round(fs*Tr2);
k2 = round(fs*Tr2)+1:round(fs*T2);

y2(k1) = y2(k1) .* fliplr(sqrt(1-(k1/k1(end)).^2));
y2(k2) = y2(k2).* fliplr(k2-k2(1))/length(k2);

% Concatenate
y = [y1 y2];

sound(y, fs);