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Tech Corner
By Technical Director Bill McQuay

audio icon Listen to sounds of the elephant bai.

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We knew that the soundscape in the Central African Republic was going to be rich; rainforest, elephants, otherworldly music of the BaAka people and insects -- lots of insects. We knew it would be a listener's delight.

So the question, should we be content with the two channel stereo recording? Certainly, this format has proven itself over the years and besides, for most of our radio listeners, stereo is the only option. But why not go the next step? Why not try surround sound? With DVD being the fastest-selling consumer electronic device ever and with surround sound home theater systems, why not make a nod to the present and try recording our expedition in a surround sound format?

We knew that if it was successful, we could at least use it as part of the road show known as Radio Expeditions Presents. These presentations, given at the request of member stations and held in theaters and auditoriums around the country, could benefit from the surround sound experience. And who knows, maybe DVD is in our future? So now the problem: how to make recordings that would satisfy both our stereo listeners and still work in the surround sound format.

After some research, I came across a paper in the Audio Engineering Society archives that suggested a four microphone set-up. OK, I thought, it's quadraphonic -- four channels instead of the current surround format of 5.1 (left front, center, right front, left surround, right surround, plus a sub woofer channel which makes up the .1 of 5.1) -- but with narration for the center channel and a little tweaking with the low frequency in the front channels in post production, I could come up with the necessary audio to satisfy the 5.1 surround format.

The problem still remained, what recording device allowed for four channel recording in the field? It had to be light, run on batteries, fairly resistant to moisture and record at least four digital audio channels. Over the years we've had success with Sony's D8 digital audio recorders, but they record only two channels. The solution, use two and sync them together in our Sonic Solutions Digital Audio Workstation in post-production. And that's what we did.

In a recording marathon lasting over 11 hours at the elephant clearing in Dzanga forest, we captured four channels of some of the wildest sounds I've heard. The only problem we encountered was when a horde of moths decided to take up residence on the microphone wind screens, creating a buzz that practically obliterated the roar of the elephants. A mosquito netting draped over the microphones solved that problem. The only other difficulty was staying awake -- the roar of the elephants provided that solution.

If you enjoyed the stereo radio pieces, look for a Radio Expeditions Presents road show in your town. If you think the elephants sound scary in stereo, you should try surrounding yourself with them.




mics covered in mosquito netting The buzz of swarming moths obliterated the sounds of elephants at night, so technical director McQuay covered the mics in netting to keep the bugs at bay.
Photo: Bill McQuay, NPR


Bill McQuay The challenges of recording in the field.
Photo: Carolyn Jensen, NPR


mics at the bai McQuay used four mics, each pair hooked to a digital audio recorder, to capture four digital audio channels. The sound was later synched together in the studio.
Photo: Bill McQuay, NPR




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