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alternate formats: sound-only .flac [download] ; sound-only [.mp3]

This test was conducted at the May 2009 "Recordist Campout," with the goal of comparing the localization (position) and depth (consistent distance) performance of stereo mic arrays. It features "pink noise" played on boom box in 15 positions at a constant distance of 100 feet in an open, natural landscape. Although several arrays were tested, at the time of this writing, I have four to compare:

Rich Peet's "Cube Mic" with 4- Audio Technica AT-3202 Mics flush-mounted in four sides of high density foam cube shape. Designed for surround, two of the mics were used for this stereo test. They are angled 90 degrees and separated 14".

David Michael's Sennheiser MKH-40/MKH-30 M-S Pair. The MKH-30 is a Figure 8 mic and the MKH-40 has a Cardioid polar pattern. Care was taken to make sure the M-S decoding was optimized in post.

Gordon Hemptom's "Fritz" or Neumann KU81i binural head mic with customized ears.

Rob Danielson's "Perp2Sphere" Mic with 2- Rode NT2000 mics in omni mode facing-forward/tangental to the sides of an 8" diameter wooden sphere.

All of the recorders were "rolling" at once so the sound stimuli are identical. The landscape is sloped at angle of about 10 degrees from left to right so other changes in apparent elevation can be attributed to differences in the mics/arrays. There is a slower-paced version of the test made with longer durations at the positions for addtional analysis.

At first, the stereo imagery of the four created pans seems similar, but by listening to the test a number of times at a comfortable sound level, differences emerge. Using processes of elimination and what they already know about mic array traits, the recordists I have shared the test with have been able to identify arrays used with a high degree of accuracy. They have pointed-out differences in horizontal spacing as well as depth (apparent distance from the mic across the stereo field) and overall consistency or smoothness. Several have commented that it helps to close one's eyes and visualize a boom box playing short excerpts of pink noise across a 200' wide landscape. The different mics used in the arrays account for much of the frequency response differences heard.

After you have noted the performance differences and allocated them to appropriate array types, here's a chart identifying the mic arrays to see how you fared.

If you would like to pose questions or leave comments about the test, you can do so in my FieldPost blog.