Sunday, February 18, 2007

Equalization To Improve Spatial Transparency

I recorded some impulses from a frozen water main repair a half block away with Rode NT2000's in a parallel boundary rig with 2.5" inset using a Sound Devices 744T recorder.

Here's a link to the recording as a 256 kps mp3 after I equalized it:

The equalization I used is based on a +10dB "lift" 1000-4000 Hz with lower-mid "notching" of the resonant tones. The concrete crusher (which sounds more like a pile driver on the frozen clay) is on the other side of a brick, three story, apartment building. All of the sound waves from the equipment are indirect reaching the rig after reflecting from local surfaces. The difference in EQ used between the two channels above 4K stems partially from noise performance in the two mics-, but also from trying to balance the pronounced hiss from a gas meter that was mostly on one side. Blue = left channel and red = right (I flipped the output after EQ).

Here's a link to the original recording for comparison, roughly volume matched also as a 256 kbs mp3.

I believe it is easier to "visualize" the location of the concrete crusher in the equalized file. The complex "stuttering" echoes created by nearby building surfaces are also more evident. Rob D.


At 6:24 AM, Blogger IM said...

Rob, I hope you write a book some day soon on field recording techniques and post-production.

At 10:54 AM, Blogger Rob D. said...

Thank you for the kind support. My work with sound has made my life fuller in countless ways. Over the last 7 years its be very rewarding to connect with more and more people around the world with similar appreciations. My first priority is helping realize a (free, cross-platform) self-archiving programming so that field recordists can create archive ready collections as they log and take notes about the recordings they have made. The work of many sound recordists still ends up on hard drives or boxes that get thrown away or are too complex for others to access and use. That is tragic. I've received lots of input from other recordists and some likely freeware integrations in mind, now I'm looking for someone with programming skills and similar interests to work with. Rob


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