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.