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The Great Pyramid: Early Reflections & Ancient Echoes

A saga of test tones, Indiana Jones, the lost knowledge of yore, a fascinating journey and much more...

Editor’s Note: This fascinating article first appeared in the July/August 2000 issue of Live Sound International. What follows encapsulates audio, acoustics, truth, fiction, legend, innuendo, road rage, taboo, and prognostication. We hope you find it fine reading for an unspoiled moment.

For some 20 years I worked for Intersonics, a company that developed experimental space flight hardware for sounding rockets and the space shuttle, and we also did contract R&D. It was while there, the Boss let me launch the Servodrive part of the company. The caveat was “as long as all it costs was space and lights.” So we were off in our “spare time” to create some “perfect bass.”

Multi-Modal TEF

With so much of the company’s NASA work having to do with acoustics and having good measurements, we were also one of the early companies to get a TEF machine. Being the main “acoustics guy,” I used the TEF to measure vibration resonances in space flight payloads and locate flaws in concrete blocks (looking for echoes).

Another task set was to measure/develop new transducers for acoustic levitation, another for producing a sonic boom. I even used TEF for measuring resonant modes on pecan shells. Let’s just say it got seriously “multi-tasked.”

While at Intersonics, a movie company asked to film the acoustic levitation process used by our space flight hardware. I ended up demonstrating it and being in the movie (“Mystery of the Sphinx” with Charlton Heston). During filming I had made a wisecrack to the producer about going to Egypt and measuring the pyramids.

Tom Danley in his lab.

Several years later, the same producer calls up out of the blue and asks if I was interested in “finding out why the inside of the Great Pyramid sounded so weird.” This would be for another movie — all expenses paid and a decent “nut” to boot.

Some quick research on the pyramid revealed it was a lot bigger than I imagined. It had a number of chambers and levels above the “King’s Chamber” — opening the possibility that it was not a “simple”acoustic system. A rough (and I mean rough) estimation of the resonance of the granite ceiling beams in the King’s Chamber put them at about 300 Hz. A somewhat less rough Helmholtz resonator and transmission line model suggested resonances starting at 2.5 Hz or so.

Into The Wild Blue Yonder

My long, fairly comfortable flight on Egypt Air from New York City landed in Cairo where my Egyptian adventure got off to a bad start.

Not being sure what to expect, or if my modeling meant anything in the real world, I’d packed two speaker systems for producing test tones, one for above 100 Hz and a second much larger unit for below. Both were shipped in sealed boxes containing a power amplifier, my trusty TEF 12, a B&K microphone, and an accelerometer (and a brace of cables).

Unfortunately, my power amplifier “got lost,” when we arrived at the Cairo airport. I suppose they thought the elaborate “tour” they took me on, through the dank, dark caverns under the airport looking for it, would offset the loss. Maybe they hoped this search party experience would combine with relentless jet lag to dissuade my pursuit.

Come to think of it, they never did pay up on the insurance claim (grumble, grumble). I was immediately on the phone to the Crown dealer in Helliopolis to arrange for indigenous amp rental. Thankfully several days of free time were scheduled before I was “on camera.”

My 01:30 trip from the Cairo airport to Giza, where the pyramids are, documented the chaos of local Egyptian “road rules.” Car horns are the “linga franca” for inter-driver communication. Headlights are almost never used at night on highways, but are frequently flashed in a fashion similar to horn honking.

Also curious, a marked 3-lane road can often have five lanes of door-to-door, bumper-to-bumper traffic, consisting of a zillion wannabe Formula 1 drivers in beat up cars. This routine requires constant lane changing, horn honking and jockeying for the pole position all at 15-30 mph.

During a return to Cairo proper, I discovered that even the traffic lights are different. Like everywhere else, green means “GO,” but yellow also means “GO” and red means “GO” if nobody is coming. A cop standing directly in front of your car means stop, but if you are in the car next to the one with the cop, you can go regardless of his hand motions or how hard he blows his whistle.

Go With The Flow

I settled in at the Movenpic hotel near the pyramids. Several days of pre-film preparation remained. It was immediately clear that many production details remained undefined.

When I asked whether or not we had any sort of production schedule, outline or anything, the answer was “it isn’t ready yet…don’t worry.” I thought that maybe that’s the way Hollywood is…real casual. So I made my best attempt to go with the flow.

The first day we went to look around the Great Pyramid (Photo 1) and the area where we needed to get to inside. The thing is huge! It’s 500 ft (152 m) across and 480 ft (146 m) high, and made of about 2.5 million 3-4 sq ft (1 sqm) blocks of limestone with interior constructed of Red Granite.

Photo 1: How the Great Pyramid looked on the cover of the July/August 2000 issue of LSI.

To enter the Great Pyramid, one must first enter the cave El-Mamun. A would-be robber bored into the limestone here in around 600 AD. This tunnel goes in approximately 50 ft (15.2 m) to a point they were supposedly about to give up, but heard a noise inside and re-directed the tunnel to the left.

There they hit the Red Granite casing on one of the interior passages and by following it (the tools they had couldn’t cut granite), they eventually located the Great Pyramid’s interior. From the end of this tunnel, one climbs about 120 ft (36.6 m) stooped over in a space barely 1 yard/meter high.

This section is fairly steep with an approximate 30-degree incline. Without the wooden boards fastened to the stone for footing, it would be almost impossible to make this climb while carrying gear. For me, this path created a whole new meaning to the term “walk like an Egyptian.”

Walking With The King

Next you enter the Grand Hall. It’s also inclined but now about 40 ft (12.2 m) tall with a corbled (stepped) ceiling. After trudging up another 120 ft (36.6 m) up the grand hall one finally reaches the entry to the King’s Chamber, which is another tunnel. This time, however, it’s level and about 10 sq.ft (1 sq.m) and perhaps 20 ft (6.1 m) long.

The King’s Chamber is about 40 ft (12.2 m) long, 20 ft (6.1 m) wide and 20 ft (6.1 m) high. The walls, floor and ceiling are all made of Red Granite. The granite blocks that make up the walls are huge. The one over the door is nearly 8 ft (2.4 m) high 14 ft (4.3 m) long and 5 ft (1.5 m) thick, yet all the blocks fit so tightly you can’t get a business card between them. They are polished to a surprisingly smooth finish.

However, it was kind of a pain just to get this far (and this was the easy part). When I expressed concern about getting the gear up to the King’s Chamber, I was encouraged to hear the producer’s plan to hire some locals to haul our gear in and out. He acknowledged the degree of difficulty, and he was right.

The producer was also right about the acoustics in the King’s Chamber. It sounded very weird inside there. Think of the “livest room” you’ve ever experienced, and then double that. It was acoustically “solid as a rock.” Given a minimum of 200 ft (61 m) of stone in all directions, it should be.

On The Skids

Our crew had a heavy heap of equipment (larger than my gear pile). So, our fearless leader decided we would go to a wood shop and have a skid made that could be dragged up the incline. After measuring the passages, we were off the next day to find a “wood shop” known to the staff’s hired Egyptian cab driver.

When we arrived at the shop, I was underwhelmed to say the least. Our wooden skid was promised to be ready in a few days. The crew (Photo 2) were already scheduled to explore/plan for other parts of the film, so I tagged along. During these few days it became obvious that the producer and his financial backers were following two somewhat different game plans.

Photo 2: Our crew at idle.

“Plan A” included the production goals that included me. Specifically, we sought to access the cavity they had found with sonar and ground penetrating radar under the paw of the Sphinx. Psychic/cult hero Edgar Cayce predicted this cavity to be there in the 1930s. 

“Plan B” was to produce a TV documentary, which overlapped Plan A as much as possible. We had permits that essentially gave us free access to everything, so we spent a couple days filming at the Sphinx compound (Photo 3). Note: I ate lunch one day sitting between its paws.

Photo 3: The Sphinx from the front paw view.

The radar also suggested there was an underground tunnel leading from the cavity, under the sphinx and continuing on. At the rear of the Sphinx, the sound guy and myself saw an opening at the bottom of its rear and after seeing no one was around, both of us went in (Photo 4).

Photo 4: The Sphinx rear entry point.

This cave has two forks. One fork goes down about 12 ft (3.6 m) and sounds hollow if you stomp on the floor. The other fork goes up into the body and stops.

There were no other ways of reaching the cavity and by this time the permit to drill a hole for a fiber optic camera had mysteriously been yanked by the antiquities department. Being problem solvers, the bosses decided to look for another way to reach the Sphinx cavity.

Optional Methods (Plans C, D & E)

The producer lived in Egypt part-time and had heard about a water well on the causeway.

The causeway, by the way, is the big stone ramp used to haul the stones up from the Nile for the Pyramid. One enters from the side through a short tunnel into the side of the actual roadway.

From here, you carefully climb over an iron gate and try NOT to fall into the 30 ft (9.1 m) deep hole immediately on the other side. Then you carefully descend a decrepit iron “ladder” down into the dark.

The bottom opens in to a room about 20 x 20 ft (6.1 x 6.1 m). At the far side is a down shaft about 6 x 6 ft (1.8 x 1.8 m) or so. You carefully get on another iron ladder (looks to be like 3/8-in round rusty steel bar) and climb down into the blackness about 60 ft (18.3 m). This was spooky. All we had for light was a helmet mounted flashlight (Photo 5).

Photo 5: Arches in the water well, author in frame.

This climb ends by opening into a tomb with three sarcophagi. They are set into deep niches in the walls. One is very large, made of smooth black stone, apparently precision made, with sharp corners even on the inside edges/ How did they do that? The other two made of limestone much smaller and in poor shape. All had been robbed.

Good To Go

After the lighting gear made it down and was set up, I immediately noticed the room was rectangular with square corners and had about 8 ft ceilings. At one edge was yet another downshaft. This one was smaller, maybe 4 x 4 ft (1.2 x 1.2 m), and went down quite a long way.

After climbing down an even worse ladder with ropes for safety, one encounters two pillars which would have held up the ceiling of the next “space” that once seemed to have been a two story room. The remains of the substantial rubble pile disguises that this room was ever man made. This level was a fairly creepy place with ample broken pottery shards and many human bones in the rubble.

The back walls are squared off. There’s a 7 ft (2.1 m) deep trench-like affair (full of water) around the back and two sides. It was like we were standing on top of the rubble pile created when the second story collapsed on the first. Anyway, they dug away a little at the center mound and about 10 in (25 cm) below the surface was a large granite slab. Radar detected a cavity below this slab about 6 ft (1.8 m) tall, and it seemed to lead off towards the Sphinx.

At this point more permits were needed so this discovery and all further work was snatched up by the head of the antiquities department.


We had gone as far as we could in the waterwell. The wooden skid was now done, and it was time for my part of the show. We had the Great Pyramid to ourselves every night after about 20:00 when the last of the sightseers depart and only the Bedouin guards remain.

As to not look the “wimp,” I grabbed a decent sized handful of cables and trudged up the slanting tunnel. When you get to the King’s Chamber, most people will have worked up a sweat. I am no marathon runner, and I had to stop at the top and catch my breath for a bit. These skinny kids come staggering up to the top with the gear and turn around go back down and get more.

The same guy carried my TEF 12 (which isn’t light), my main woofer (which was 80 lbs), and three trips of lighting batteries (each is a big car battery in a plastic cooler). I was impressed. And I realized that I was a wimp and there was no way around it. From then on when the crew hired locals to carry everything I knew they were earning a good wage — by local standards.

The lighting guy tapped into the AC mains (240-volt, 50 Hz) and set up his transformer, and we were ready. I picked a spot on the wall in the King’s Chamber to set up my stuff. I placed the source at one wall and the microphone at the opposite wall and was ready to go.

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