Week three: Recordings with contact mics and portable recorder

09Jul10

This Thursday at the site I was concentrating on recording rather than digging (although, incidentally, I found loads of shellac pieces on the surface close to a test hole I’d already dug).

contact mics on metal plate

contact mic on metal plate

The two images above show contact mics on the metal plates used to board up the windows of the old building. I recorded the ambient sound of the site through two contact mics. The recordings are surprisingly clear, with even birdsong being picked up, but everything has a slight metallic decay and certain frequencies, such as passing cars, resonate the plate. The wind blowing the plates also comes through clearly.

I also experimented with another piece of galvanised steel to try and pick up the raindrops.

resonating metal plate with piezo transducer

resonating and recording metal plate

Next I used a contact mic as a resonator on the metal plate, by feeding a signal through an amp and a transformer.

contact mic on wood hit by leaves, also showing amp

The signal was of another contact mic on a piece of wood, which picked up the sounds of plants’ leaves hitting it as they blew in the wind.  While the resonator didn’t make sounds clearly audible by ear, as I’d hoped, the contact mics picked the sound up very clearly, again with the wind sound from the plate and the metallic plate-reverb feel.

In the morning I also bought a violin bow. I’d planned to try and get some sounds from the metal gate at the site entrance, though it didn’t seem resonant enough.  I did spend quite a long time playing the spades, shovels and a rake that I’d used for digging earlier, as well as a billy can and piece of galvanised metal which were around. The tones were generally quite grating, somewhat like a badly played violin and sometimes like guitar feedback. I did enjoy using the billy can – a rectangular aluminium saucepan – as I could get two tones simultaneously by playing the two opposite sides of the rectangle.

recording environmental sound from the bottom of a hole

The last two recordings I made were of the ambient sound of the site, first from the bottom of the first test excavation. The small space is acoustically dead-sounding, despite being only 50cm below ground level. For the last recording I attached contact mics to the corrugated ceiling of the shed at the back of the site. A warm sounding recording of raindrops and traffic noise.

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One Response to “Week three: Recordings with contact mics and portable recorder”

  1. 1 electronicmusik

    Amazing stuff Graham ……….


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