LA GROTTA GIGANTE

A world record

To begin with, the Giant Cave, located in the Trieste Karst, is the world’s largest single-chamber tourist cave. This alone would be enough to entice a visit. It goes without saying that in such a space, the acoustics are also record-breaking.

Outside and inside

Just a few steps downward. Already after the first ramps, you realize that something has changed. The sounds are muffled, as if you had entered a small living room with velvet-lined walls.
Suddenly the outside no longer exists.

The noise of the highway in the distance, the singing of birds, the wind through the leaves of trees, all the sounds of the surface world have disappeared and a sensation of “interior,” of intimacy prevails. If you’re lucky enough to be in a discreet and not too large group of visitors, the effect is noticeable and the sensation is such that voices lower and a sense of awe is created, of respect, as toward a sacred place.

The concert of water drops

If it has rained in the previous days, in this section and along the entire first descent you can hear the water drops, which falling on the metal railings sound in many different ways. Depending on the timing and locations of precipitation, the “water drop concert” can be sparse, placid, or very sustained. The “notes” have a small musical tail if the drop hits the right spot on the railing, or they can be dry, very brief and more or less sharp if they fall on a stalagmite or on concrete or on our jackets. And they are not only distributed on the horizon, but also above and below, and they are near and distant, giving a pleasant and relaxing sensation.
The sound in this first section is still quite muffled, the drops can be heard clearly, there’s no particular reverberation. Until…
Suddenly it opens up.

An underground cathedral

An underground cathedral presents itself to the eyes and there’s no photograph or recording that can convey the idea. The acoustics have also completely changed, opening up to fill the entire surrounding space. It’s practically impossible to resist making some sound to hear its echo.
After a few steps you reach the center of the hall.

If there’s water, the acoustic panorama is total, the drops are everywhere within a radius of seventy meters and a height of over one hundred. They sound very differently depending on whether they fall on the light fixtures (this is a bit ugly, it must be said. Some work could be done on this) on the railings or on the roof of the geophysical station visible at the base of the cave.

It’s not often you get to listen to rain in a cathedral! The reverberation is not particularly long, a first reflection is followed by a seven/eight-second tail with a soft, sweet and dense sound without being redundant. Unlike cathedrals, where the walls are largely marble and smooth, here the walls are full of recesses, bends, sculptures, surfaces with countless faces, roundness, and the sound doesn’t bounce uniformly, but in infinite ways, times and directions. The immense void of the cavity only amplifies its volume. Obviously all this makes very delicate sounds pleasant, while a noisy audience could make listening tiring, exhausting.

An acoustic labyrinth

When there’s no water infiltration and therefore the drops don’t fall or are very sparse, the cave’s acoustics are still impressive. Our guide defined it as “a noisy silence,” which still holds surprising peculiarities. There are points where the sound goes downward or others where you can hear the voices of people very far away as if they were just a few steps away. If there’s silence, even an infinitesimal sound can be heard from very far away, a voice in the tunnel at the exit can be distinguished very well from below, even if “blurred.”
The guides and speleologists who have worked in the cave for a long time know all these secrets well and we invite you to ask them all questions about it.