download the audio file 2.wav.gz

hints :

• Setup baudline to be a Netscape helper application as described in the FAQ.
• Ignore the 60 Hz AC power leakage and its harmonics (120 Hz, 180 Hz).
• Turn on the 60 Hz notch filter in the play deck.
• Try playing the mystery signal at different speeds, slow it down or drop it an octave.
• Loop on the transitional points, play it again and again until you start to hear things.
• Measure the harmonic relationships with baudline's harmonic helper bars.  Use this handy tool to determine the fundamentals.
• Look at the major frequency rise at the start, and the fall near the end.  How are they different?  What is going on?
• Look for clues in the four blips during the steady state part.  Model that behavior.

What is it?

Click here for the answer.