Correction!
Just read their paper in detail (J. Acoust. Soc. Am. Vol 119, No 2) and Benjamin Lange WAS included in the main experimentation and analysis. The downer is that a 1.21 metre length of PVC pipe was used as the instrument, which is good news for you plastic-heads
Also, there is an interesting finding in figure 5 of this paper - the crux of their hypothesis! - which makes Lange stand out from the two balanda-style players when using a high tongue position (though this is not discussed!). If I understand this correctly, unlike both balanda players, a clear vocal tract impedence maximum could not be discerned for Lange, which is curious given the restriction made by the tongue. This suggests Lange was compensating to keep mouth air pressure constant regardless of tongue position, whereas both balandas allowed pressure to vary (didn't Guan drum this into us years ago?
). Vocal tract impedence was measured on one breath, so CB differences cannot account for this.
It's a shame more measurements weren't done for Lange, otherwise we'd have also been able to speculate on the spread of data points for both balanda players as opposed to the apparently close-knit group for Lange, but that would require a second packet of biscuits...
