Eavesdropping On History

[R. A. Hettinga]

http://www.nytimes.com/library/magazine/home/20001203mag-hitt.html

Eavesdropping On History

New technology perfected by Stephen St.Croix is recovering long-lost
sounds. It might even bring back Watergate's famous 18 1/2-minute gap. By
JACK HITT


 Stephen St.Croix operates under the principle that no tape erasure is
complete. Photograph by Deborah Mesa-Pelly.
------------------------------------------------------------------------

he National Archives in Washington recently received an extraordinary
request from Stephen St.Croix, who is the president of a company called
Intelligent Devices. St.Croix is an expert in the esoteric field of sound
extraction, and he proposes to solve one of Washington's most enduring
mysteries: what was on the 18 1/2-minute gap on the Watergate tape? He
believes he can retrieve the sound from a tape that may have been erased as
many as five times more than 25 years ago.

The very notion of St.Croix's vocation conjures images of a world of
paranoid but talented ex-spooks twitching with suspicions. To find out just
how possible it was to dig, archaeologically, in the realm of old sound, I
called Intelligent Devices to talk to St.Croix. Days passed before he
returned the call, and when he finally did, my 5-year-old daughter picked
up the phone (right after I did) and then clumsily hung it up.


"Is someone listening in on this conversation?" St.Croix demanded. When I
explained what had happened, he paused for a moment, as if to determine
whether my explanation was just a fast-thinking coverup. Then he seemed to
relax.

"You know, if you're paranoid and they are listening," he said almost
cheerfully, "then you're not paranoid." St.Croix agreed to let me visit
him, but because of security concerns, I was told to come to his house, not
the office. He didn't want me to publish the name of the town he lives in
except to say that it's outside Washington. He gave me precise instructions
for the cabby. I was told to get out at the end of a certain cul-de-sac.

------------------------------------------------------------------------
Jack Hitt, a contributing writer for the magazine, recently wrote about
piracy on the high seas.
------------------------------------------------------------------------


"Then wait for the cab to leave," he said. "I'm serious. And after you're
sure the cab's gone, walk down the driveway to the left. Don't come to the
front door. Just keep walking. You'll set off the lasers in my woods. I'll
know you're coming and come out to meet you."

It went off without a hitch. As I approached a side door, a trim,
well-built 52-year-old St.Croix, dressed in black boots, black pants and a
black shirt, stepped out to greet me. He has the eyes of a young Gerald
Ford and close-cropped gray hair, which is a new look for him. His driver's
license from just a few years ago shows a biker guy with about two or three
feet of blond hair. St.Croix escorted me to his living room. He rocked in a
black leather chair and talked while playing an unamplified electric guitar.

St.Croix was a session player for most of his life, and his studio wall
holds a platinum record for Stevie Wonder's album "Songs in the Key of
Life." In the mid-1980's, he gravitated to the lucrative field of audio
cleanup, restoring and improving the sound for movie classics like "The
Wizard of Oz" and "Gone With the Wind." St.Croix may be a handsome
biker-surfer dude with lots of modern toys, but in his heart he's a sound
guy, a techie. It took a while for him to channel his inner dweeb. But once
he appeared, St.Croix was quite happily talking the shoptalk of a sound
geek who thinks extracting hidden voices from fuzzy tape is just really
cool.

He loaded his G3 Mac with Speech Extraction System, the software his
company sells, and fed a segment of audiotape into the computer. I snapped
on my headphones and heard nothing but roars and crackles with some kind of
human voice deeply buried in the cacophony. "These are the tools one works
with," he explained, pointing down the side of the work screen. The menu
bar offered Noise Reduction and Bandwidth Limiter and Harmonic Notch and
Tone Removal and Adaptive Extraction. He explained that the recording was
an authentic piece of tape made by a reporter aboard Air Force One a few
years ago.

"This feature cuts out the rumble of the airplane," he said. By clicking
the button and moving the cursor, you can remove all the sound that is
naturally outside the register of the human voice. By just lopping off
mostly bass sound and a bit of treble, I could almost make out the words
being uttered in what was obviously a conversation between two men.
St.Croix ran the remaining sound through the Adaptive Extraction module,
which "listens to the audio and rewrites its own code to better fit what it
hears." As he cycled the sound through repeatedly, the sound got better and
better. Pretty soon, I could hear President Clinton and President Bush
talking to reporters as they flew to the funeral of Yitzhak Rabin.

That was a pretty easy problem to solve. To show me something trickier,
St.Croix loaded a recording from a case he had worked on a while back.
"It's a drug dealer arranging a pickup," he said. "He's talking on the
telephone, but he installed sound distorters that completely mask the
conversation." I heard a variety of irritating mechanical noises, although
threaded deeply in the background was the inaudibly basslike "mmmm"'s of
human intonation. It was as if the speaker were talking underwater with his
mouth closed.

St.Croix ran the segment through the Tone Removal system. Tones are sounds
that maintain the same frequency and volume. Human language is highly
intonated; that is, it is constantly changing frequency and volume. The
Tone Removal module analyzes the sound, recognizes the frequencies that are
constant and then strips them out. It cleaned up the sound enough for me to
tell there was human conversation on the tape, but it was still
unintelligible. Then St.Croix began to loop it through the Noise Reduction
module. It never reached broadcast quality, but what began as a dense
murmur became an audible voice saying: "Take the package and go back and
drop it off. . . . Meanwhile keep an eye out for other people. Don't talk
to anybody. If anybody asks, don't panic. You don't know anything."

Until recently, recovery efforts were limited by analog sound. For a
technician to cut out a piece of bad sound, it had to be "notched" out the
way you chop at a tree. While you could get the bad sound out, you also had
to remove parts of the sound you wanted to keep. With analog, there was a
built-in limit to any recovery job. But computers changed all that.

"Digital allows you to make square cuts," St.Croix said. He demonstrated
how an unwanted piece of sound on one part of the sound curve was right
beside some speck of voice. Then he digitally extracted the unwanted noise,
like slicing down a length of fabric with a razor blade to remove a single
thread. The computer allowed him to do this repeatedly -- hundreds and
thousands of times, removing microscopic bits and flecks of tones and
rumbles and hisses. The crackle and hum slowly faded as the coherent
conversation of human voices rose to the surface.

t was early morning and St. Croix wanted breakfast. He took about five
minutes to load a fanny pack with some electronic gear. St.Croix is a gizmo
fiend. He has a feeling of mechanistic intimacy that probably dates back to
a long-ago reading of "Zen and the Art of Motorcycle Maintenance." His
house is packed with dust-free objects of high tech, and in his driveway he
has three race cars and half a dozen motorcycles. We climbed into his
cherry red Corvette -- fully customized by St.Croix with a radar detector
that can even warn of cops in helicopters -- and rumbled up the driveway.
St.Croix flipped open his cell phone like Captain Kirk and, addressing
someone or something, explained that we were leaving and to "arm" the
house. He turned out of the cul-de-sac and punched it.

At a local diner, St.Croix explained his Watergate theory. Audiotape, he
said, is basically rust painted onto a piece of tape. "Iron oxide has many
interesting properties, it turns out," he said. "It catches and releases
oxygen very easily. That's why we have iron in our blood, to regulate
oxygen flow. We're basically rust, too. But on a piece of tape, if you
could look at it closely, you would see an array of randomly placed iron
particles. What a tape recorder does is set these in a particular order
that can then be reproduced as sound."
'In an urban environment, it wouldn't be hard these days to reconstruct a
conversation you thought you were having privately walking down the street.'




Erasing a tape simply takes the patterns set in the iron-oxide particles
and scatters them randomly so that, when played, what you hear is the
familiar hiss of blank tape. In the past, several sound technicians have
had a go at the Watergate gap, but what they tried to do was retrieve the
sound by listening at the outer edges of the tape. The theory was that the
eraser head was a bit smaller than the recording head, so that some sound
might have been preserved at the hem of the tape. St.Croix operates from a
different theory.

"No erasure is complete," he said. "The head rescrambles the sound filings
but usually only gets about 95 percent. Even if they erased it numerous
times, each time they only really get about 95 percent. Which means that
there is a possibility that buried in there is the original sound."
St.Croix proposes to build a special tape machine with 200 separate heads
that would read the piece of quarter-inch tape. The computer would be
programmed to eliminate the randomly situated particles and read only the
ones that, on each vertical strip passing through the heads, are the same;
that is, the particles that represent the remnants of coherent sound.

To persuade officials at the National Archives, St.Croix is proceeding with
an experiment -- he'll record on an old tape from the 70's and erase its
content several times, then try to recover that sound. If it works, a
committee at the archives will then vote on whether to give St.Croix a shot
at the Watergate tape and the opportunity to excavate the secret that Nixon
took to his grave. We know from written logs that it is a conversation
between Nixon and Bob Haldeman on June 20, 1972, three days after the
break-in. Nixon's accusers have always assumed that the gap was really a
recording of the two men planning the coverup. Nixon's defenders have
always supported the president's claim that this swath of tape was
accidentally erased when Nixon's secretary mistakenly hit a pedal-triggered
erase button with her foot. Sound technicians are dubious of Nixon's claim
about his secretary because within the gap can be heard the clicks of
someone turning the machine on and off about five times. That's a lot of
mistakes, they argue, unless the secretary's foot was temporarily seized by
palsy.

Sound ends up as heat," St.Croix mused later in the morning. "We speak, and
the sound waves vibrate the molecules in the air, bounce off the walls and
vibrate the molecules some more but ultimately dissipate as friction, as
heat." And increasingly, he said, those waves are getting captured
somewhere.

"When you walk down the street, there are any number of video and even
audio devices pointed at you," St.Croix said. "In an urban environment, it
wouldn't be hard these days to reconstruct a conversation you thought you
were having privately walking down the street."

One of the more peculiar theories about sound was developed hypothetically
some 30 years ago. A technician named Richard Woodbridge III coined the
phrase "acoustic archaeology" in the August 1969 issue of Proceedings of
the I.E.E.E., the engineering journal. Woodbridge theorized that there were
many occasions when sound might innocently get scooped out of the air and
preserved. For example, when an ancient potter typically held a flat stick
against a rotating pot, he was accidentally (and crudely) recording into
the clay the sounds around him. Woodbridge wrote about experiments he
performed pulling basic noises off a pot. Another experiment involved
setting up a canvas and then talking while making different brush strokes.

"This is to record the finding of a spoken word in an oil portrait,"
Woodbridge wrote. "The word was 'blue' and was located in a blue paint
stroke -- as if the artist was talking to himself or to the subject.
Parenthetically, the search was long and tedious. The principle, however,
was established."

St.Croix listened to my recounting of Woodbridge's theories on our way home
from breakfast, and fishtailing at 80 miles per hour, he said to me, "Let's
don't go overboard." He then cocked his cell phone. "Disarm," he whispered,
and without encountering any cross-fire, we pulled peaceably into his
driveway. Safely nested back within the sanctuary of his electromagnetic
web, St.Croix began to recall some rather Woodbridgean work he had done on
"The Wizard of Oz." He explained that there were certain audible
peculiarities if you listened carefully to the master sound reel. For
instance, you might hear a piece of music that involved a flute and a
timpani, yet most of the timpani bass sound was too low in frequency to be
recorded by the equipment available in 1939, when the movie was made. But
the recording of the flute had a mild Doppler effect, as if something were
making the flute throb in and out. St.Croix realized that this phantom
effect was a result of the lost bass parts of the timpani.

"So it was a kind of sound scarring," he said. "We analyzed it and were
able to go back and restore some sound at the limits of the audio -- some
bass, some treble -- that wasn't even there in the master recording but was
there in the original recording session."

As we walked up his driveway through the leaves (and lasers), St.Croix
called me a cab on his cordless phone, and then we sat down and waited for
it, chatting idly. Considering the piece of plastic in his hand, he said:
"This is just a standard cordless. But I have had it especially encrypted.
The phone is good and safe." He looked at the receiver admiringly. "It's
kinda nice." We stretched out our legs on the asphalt. The early afternoon
light was just beginning to angle. There was nothing left to say. Sunbeams
shot majestically through trees whose orange-brown leaves drifted down
continuously in a familiar October rustle. We listened to the sounds of
autumn. They have never sounded so loud.

-- 
-----------------
R. A. Hettinga <mailto: rah at ibuc.com>
The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'

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