The exact functions of the Great Pyramid’s interior chambers remain a complete mystery. It has always been assumed that the monument’s King’s Chamber, Queen’s Chamber, and the Subterranean Chamber were all designed with funerary considerations in mind, arguably the interment of its builder. This was the Fourth Dynasty pharaoh Khufu, who reigned circa 2609–2584 BC, at the height of Egypt’s Old Kingdom period .

This investigation looks at the following questions: Does the Great Pyramid incorporate sound technology and does its Dead-end passage function as an infrasound generator?

Only the uppermost of the three rooms, the King’s Chamber, contains a sarcophagus in which a cadaver might have been laid to rest. Even in this knowledge, there is no proof that this was the room’s primary usage.

Very likely each room had its own unique function, although what this might have been remains unclear. Yet one persistent, recurring fact that cannot be unconnected with this enigma is something pointed out by many visitors to the Great Pyramid , this being that all its chambers appear to possess striking acoustic properties.

A perfect opportunity to better understand the acoustic qualities of the Great Pyramid’s mysterious inner chambers recently presented itself. A party of 16 individuals visiting the monument were asked to switch on the voice recorders on their smart phones before entering the building (no one else was present, other than a single inspector who remained in the King’s Chamber).

The devices were then left on to record for approximately one hour as a series of simple tasks were conducted in the King’s Chamber and also in the enigmatic Subterranean Chamber. This is located deep below the pyramid in the bedrock, at the end of the so-called Descending Passage .

Subterranean Chamber

I personally led the party of five that went down to the Subterranean Chamber. On arrival all recording devices were placed at the entrance to the room’s Dead-end Passage, the narrow, 53 foot (16.2 meter) long tunnel at ground level that heads south from the southeast corner of the room. Earlier, British engineer Rodney Hale had suggested that this enigmatic feature might have functioned as a resonance tube. This was for two reasons: 1) its long, pipe-like appearance, and 2) the fact that it had been deliberately cut and dressed along its entire length, indicating that it must have had a true function, and was not, as Egyptologists believe, an abandoned passage of no particular interest or importance.

It was a theory I felt warranted further exploration, with this in mind I crawled on hands and knees along the entire length of the tube, taking with me my own main recording device (this being a Blackberry Classic with a built-in, high quality microphone and recorder). Once at its end, I turned to face the entrance and intoned three times with short pauses in between.

The Subterranean Chamber’s Dead-end Passage, looking south towards its far end. It is 16.245 meters in length and 0.775 metres in width, giving its dimensions an approximate ratio of 21:1. (Image: © Andrew Collins 2019)

I then vacated the tube and a female, J (name withheld), took my place and did the same. On completion, a five-minute period of relative silence was recorded inside the Subterranean Chamber to examine ambient background noise against any deliberate sounds made in the same room.

King’s Chamber

At a pre-designated time, the remainder of the party, consisting of eleven individuals, placed a single recording device in the King Chamber’s red granite sarcophagus. A female then climbed inside the sarcophagus and intoned three times with short pauses in between; this being followed by a male, who did the same.

The King’s Chamber inside the Great Pyramid, showing its red granite sarcophagus. (Image: © Andrew Collins 2019)

At the same time the group in the Subterranean Chamber remained silent as I climbed back into the Dead-end Passage and lay on my back at its far end. I then fell silent for around 15 minutes to determine whether sounds made in the King’s Chamber could be heard here, a claim made as far back as 1988 by Egyptological researcher Larry D. Hunter .

Although I did hear and record a number of unexplainable knocks when inside the tube, none corresponded with any of the sounds recorded at the same time in the King’s Chamber.

Queen’s Chamber

One of the group, K (name withheld), conducted a lone vigil in the Queen’s Chamber . This lies beneath the King’s Chamber and some distance above the Subterranean Chamber. Here she remained in virtual silence until 10 minutes after the main experiment, at which point she sang verses of the hymn “Amazing Grace”. This allowed us to examine the resonant frequencies of the Queen’s Chamber, as well as establish whether sounds made in the Queen’s Chamber could be heard in any other chamber.

The niche in the eastern wall of the Great Pyramid’s Queen’s Chamber. (Image: © Andrew Collins 2019)

Sounds Between Chambers

An examination of the recordings made in the Subterranean Chamber by Hale showed no trace of K’s rendition of “Amazing Grace” inside the Queen’s Chamber. This suggests that sounds from the Queen’s Chamber cannot be heard in the Subterranean Chamber. In contrast, sounds made in the Queen’s Chamber can be heard in the King’s Chamber, since K’s rendition of “Amazing Grace” was discerned both audibly and in recordings (see fig. 1).

Fig. 1. Comparison of the spectrograms of a) K singing “Amazing Grace” in the Queen’s Chamber, b) K’s singing recorded at the same time in the King’s Chamber, and c) Andrew Collins’ recording of K’s voice when she sang further verses of the hymn in the King’s Chamber at a later point in the session. The three plots all have the same time scale. (Image: © Andrew Collins 2019)

If correct, then this upward conveyance of sound from one chamber to another via the vaulted Grand Gallery might well be linked with their primary function. Beyond all this, and for completion, Hale determined that sounds made in the Subterranean Chamber were not recorded in either the Queen’s Chamber or King’s Chamber.

Peaks of Activity

Reviewing the twenty-three hour-long sound recordings made by all sixteen individuals on an assortment of smart phones (some of the party used two devices simultaneously), Hale found that, even when silent, persistent levels of very low frequency (VLF) sounds were present in the ambient noise produced in all the main chambers (see fig. 2).

Fig. 2. Spectrograms of natural sound resonance from the various chambers of the Great Pyramid (King’s Chamber, Queen’s Chamber, Dead-end Passage, and Subterranean Chamber) as recorded in virtual silence. The darker bands indicate stronger amplitudes. All frequencies are either VLF (125-20 Hz) or within the infrasound range (20-1 Hz). (Image: © Andrew Collins 2019)

The largest amplitude sound frequency recorded in the King’s Chamber was at 49.5 Hz (see fig. 3). Significant spikes of activity occurred also at 30.5 Hz and 33 Hz with a cluster of peaks between 30 Hz and 130 Hz. In the Queen’s Chamber spikes of activity occur at 118 Hz and 120 Hz with others between 94.5 Hz and 125.5 Hz.

Fig 3. Plotted frequency spectra of the King’s Chamber, Queen’s Chamber, Subterranean Chamber, and the latter’s Dead-end Passage. Data selected for examination using Audacity and Excel software came from the pre-arranged quiet periods during the visit. Five recordings were used for the Kings Chamber and five also for the Subterranean Chamber. Just a single recording was used for the Queens Chamber and Dead-end Passage. No low frequency boosts were given to any recording to better display lower frequencies, so the results given are unmodified. (Image: © Andrew Collins 2019)

In the Subterranean Chamber the resonant frequencies were found to be quite different to those of the King’s Chamber and Queen’s Chamber. Significant spikes are seen at 30 Hz, 32 Hz and 52 Hz, and also at 15 Hz and 19.75 Hz, these last two being within the infrasonic range (20 Hz to 1 Hz), meaning that they are completely inaudible to the human ear.

A similar peak of infrasound activity at 15 Hz was noted also in connection with the King’s Chamber. These infrasonic sounds were all recorded in near perfect silence, and so with the assumed lack of sensitivity of some of the voice recorders below 20 Hz it means that these peaks in infrasound are almost certainly much stronger still.

Inside the Dead-end Passage

Inside the Subterranean Chamber’s Dead-end Passage (see fig. 4) all the main peaks of activity fell within a frequency range of between 5 Hz and 95 Hz, with pronounced spikes at 25 Hz, 26 Hz and 35.75 Hz.

Fig. 4. Cross section of the Great Pyramid showing its various interior chambers along with the Dead-end Passage at the southern end of the Subterranean Chamber. (Image: © Andrew Collins 2019)

The most striking finding with respect to the Dead-end Passage was the strong presence of infrasound. There were spikes of activity at 5.13 Hz and 16.13 Hz (see fig. 5). That seen at 5.13 Hz must be very strong indeed for it to have been recorded on a smart phone voice recorder (in this instance the inbuilt microphone and recorder of my Blackberry Classic device). Indeed, it is most likely much greater in amplitude than the 16.13 Hz spike, which would have been slightly easier for the recording device to pick up.

Fig. 5. The resonant frequencies of the Subterranean Chamber’s Dead-end Passage based on four quiet periods, each 3.5 minutes in length. (Image: © Andrew Collins 2019)

Prior to our visit, Hale had predicted that, based on the Dead-end Passage’s approximate length of 53 feet (16.2 meters) its resonant frequency and odd-number harmonics (going up in multiples of 3, 5, 7, etc., would be approximately 5.3 Hz, 15.9 Hz (3 x 5.3), 26.5 Hz (5 x 5.3), 37.1 Hz (7 x 5.3), and so on. These figures match very well the recorded peaks of activity at 5.13 Hz, 16.13 Hz, 25-26 Hz, and 35-36 Hz, which ably reflect the tube’s primary resonant frequencies based on its approximate dimensions.

To check these findings, I was able to determine that the true length of the Dead-end Passage is in fact 53 feet (16.2 meters), with a maximum width of 2.5 feet (0.775 meters) (going down to 2.46 feet (0.75 meters) further inside the shaft) and an internal height of 2.49 feet (0.76 meters). Hale then used these dimensions to more accurately calculate the tube’s fundamental frequency, which turns out to be 5.18 Hz, with a third harmonic of 15.54 Hz and fifth harmonic of 25.9 Hz, which are even closer to the tube’s recorded resonant frequencies. Of potential interest here is the fact that the length to width ratio of the Dead-end Passage is approximately 21:1, indicating that the dimensions of the passage might themselves be very specific in nature (see fig. 6).

Fig. 6. Reconstruction of the Dead-end Passage showing the 21:1 ratio of its dimensions. (Image: © Andrew Collins 2019)

What all this suggests is that the Dead-end Passage was indeed designed to function as a resonance tube, producing infrasound with a base frequency of around 5 Hz. Yet if this is the case, what is so important about infrasound and were such sub-aural sounds known to the ancients? In part two of this article we will see that infrasound is now thought responsible for not only feelings of disconnection and otherworldliness, but that its presence can also lead to both psychic experiences and paranormal happenings.

We will also see that the that effects of infrasound have been used in the design of ritual buildings and in achieving a sense of connection with the supernatural since the first invention of musical instruments in the Palaeolithic age. Yet if this is the case, what does it tell us about the apparently deliberate presence of infrasound and very low frequencies inside Egypt’s Great Pyramid over 4,500 years ago?

Top image: Stairway of the tomb in the center of the Great Pyramid. Source: witthaya / Adobe Stock.

Go to Part 2: Exploring Infrasound Technology Use By The Ancients

By Andrew Collins

This article was written with additional information provided by Rodney Hale, C Eng. MIET.