(CNN) The latest on the missing Saudi journalist.
It exists. If you’ve been wondering why the Turks have not released, here’s the explanation.
The Turks allege that the recordings came from an Apple watch, but this is not possible. Robert Baer has pointed out that the Turks bug consulates as a matter of course. Implanted bugs are the likely source of the audio.
The problem for the Turks is that a microphone, and the associated electronics, have a finger-print of type that is impossible to mimic well. Contributing elements:
- Every microphone is a noise generator, of both Brownian noise, and Kelvin noise from the electronics.
- The part of a mic that captures sound is like a drum head, with its own individual tones and modes that differ even between different units of the same model.
- The boundary reinforcement effect changes the sound that the mike itself hears, by 6 decibels per octave per surface. A microphone on a wristwatch hears very differently from one connected to a flat wall by a tiny tube.
- The microphone signal is never transmitted verbatim. It is converted to numbers by an analog-to-digital converter. The stream of numbers is then reduced in size by one of many CODECs, coder-decoder combinations.
- The analog-to-digital converter adds many artifacts to the signal: quantization noise, spurious tones and combinations of tones, sidebands, harmonic and inter-modulation distortion, and idle tones, present when there is no sound at all.
- The CODEC continues to mess with the sound, adding more artifacts, and deleting many things the ear cannot hear, but which laboratory instruments can easily measure.
So how can the sound of an Apple watch be disguised? By degrading it with noise and distortion, both the Apple origin, and the intelligibility of Khashoggi’s screams are simultaneously obscured. Notch-filtering some artifacts and adding others adds further confusion. If they have the sophistication, the Turks might try modeling the “drum head” of an Apple Watch microphone. But the signature of the original “drum head” cannot be obliterated, only obscured.
Turkish engineers are doubtless busy running the audio through signal transformations in line with the above. These days, it’s all done with computer algorithms, with little need for special hardware. We wait while the Turks cook the audio, and taste-test the result, which can be frustrating or awful. For it must serve two purposes, or sacrifice one:
- Disguise the true origin, from microphones implanted in the structure of the consulate, while faking the artifacts of Apple Watch audio.
- In opposition to the above, leave Khashoggi’s last words intelligible enough to prove a point.
Rather than release self-incriminating audio, the Turks may choose to let Saudi off the hook. Pressing the point could sacrifice every bugged consulate in Istanbul.
Knowing your consulate is bugged is half the battle. The other half is merely the cost of razing it to the ground, or living with big ears.