Listening To Sound in the Ground

Earlier this year I started listening to sounds from the ground, and used AKG and PIEZZO microphones attached to metal sheets and shoved into our allotment clay soil to pick up and listen to what sounds  I could.

The results were intriguing, and question arose about the behavior of the microphones and what I was exactly hearing.

What was the sound source, and what was the low frequency white noise I was picking up?

Questions came up like -Do totally submerged microphones pick this white noise up, and what were the sound frequencies from the local traffic and what was from sources further away?

Here’s the spot near the Clifton Suspension Bridge where I put in the metal plate, and below  an AKG pick up microphone on a rock face not far from the road by the bridge.

As I did more tests, it became clearer to ask testable questions  – using comparisons. So comparing different sized metal plates, burying them differently in the ground, setting them out at different distances from the road, told me a bit more about the sound.

Questions started forming like: what sound came from above ground and what from underneath, which settings on the equipment should I adjust? In fact how did the different equipment compare?

I did distrust my equipment somewhat and I looked for other microphones I had heard of. My quest to look into equipment had begun.

Sounding Plymouth Sound

On the 3rd July 2009 we received sounds from round the bay at Plymouth Sound: a hydrophone deep under water and met balloons from high above the sea. Mobile phones and radio transmitters to a desk on the Hoe for-shore sent these sounds, where they could be heard on speakers. Ambient and orchestrated sounds were used to describe the grand site: a sonic circus of information.

A great team of ‘players’ came to operate the sounds and equipment – 15 in all, including the boat operators.

Two boats set out for the 10.45am sound check. The Black Pig – University dive boat by Drakes Island had a radio transmitter – at sea level – on deck, and bunch of tethered met balloons with a mobile phone above the sea at varying levels between 15 and 30 meters up.

The Sea Trek was transmitting their sounds from a hydrophone at between 1 and 10 meters in the water, and were situated near the Asia buoy just out of the deep channel.


Explosives were set on near the Folly on Mount Edgcumbe on the Cornish side of the bay, the furthest to transmit to us at 2.75 kilometres, and a ships bell was situated on Mount Batten Sea Wall on the Devon side of the bay.

Met balloons were flown from the Devon side and recorded from 50 meters above sea level, and subsequently let go into the atmosphere.

At the sound desk with radio receivers and mobiles plugged in, we over came obstacles, like buzzing transmitters and explosives that didn’t go off first time, and were able to relay sounds out loud on speakers. Recordings were made of the individual places and also mixes from the main desk.

Water and Rock There’s a deep ocean channel under the water hidden and ancient
Evolved from a fresh water flow to a valley fathoms below the salt
Time is described by the slow erosion of rock under the tide
The rock imperceptibly
And steadily

Humankind to-ing and fro-ing in craft
Milling, pottering, circumnavigating, cruising, setting out, arriving home, chugging, paddling, steaming and running in front of the wind