8/4/2015, Errol, Carse of Gowrie
Meet Paul in the square in Errol at 2pm our mission today to record the acoustic signature of the kilns at Errol Brickworks, now a Mackies Potato crisp factory. The kilns stand as a monument to the prior industry, having only previously seen archive photographs of the kilns I had high expectations for the acoustic quality to be found within.
Paul had organised our visit with the owner, upon arriving the kilns were obvious, 2 side by side, squat dome shaped structures as wide as they are high. The internal diameter after analysis was found to be 5.5m by 6.5 m in height at the highest point of the dome and floor proving to be several feet lower than the ground outside. We were able to access only one of the kilns on the day of our arrival, this kiln having no door the other locked. A repeat visit would be worth while to measure the other kiln for comparison purposes.
Paul brought along his guitar, so along with the sine sweep and balloon burst impulse response (IR) recordings Paul performed a live improv inspired by the space and the moment, having at one point to respond to the sound of air brakes and the not too distant sound of a lorry leaving the factory 500m's away!
The kiln when entered for the first time was acoustically disappointing, appearing to have very little natural reverberation decay. The space proved more interesting after walking around and listening for a while, at one point I had clambered over the rubble strewn floor (mostly bricks and brick dust) further towards the opposite wall from the entrance. The sound of Paul's footsteps near the entrance approached the quality of the whispering gallery in the dome of St Paul's cathedral in London, albeit on a small physical scale, a distinct delay in what I was seeing and then the sound I heard being transmitted in stereo behind me along the inside edge of the wall. In analysis of the IR this manifested itself as a short but very pronounced pre-delay, the total reverb decay time in the kiln is approximately 0.87 seconds.
Post script: on the way home from the Errol Brickworks field recording session, I opportunistically stopped at the roadside just outside Abernyte, vaulted a fence and Meade my way to a disused grain silo spotted on the way to Errol. Having swiftly obtained an IR recording using a balloon I had 2 Field recorded IR's in the bag in one day. The grain silo, 20m's tall, cylindrical and made of concrete exhibited a reverberation decay time of 8.5 seconds long?
The rambling thoughts and musings of an audio engineer/sound designer turned archaeoacoustician