My Year of Darwin (2/6/2014)

"The noise from the insects is so loud, that it may be heard even in a vessel anchored several hundred yards from the shore; yet within the recesses of the forest a universal silence appears to reign" -Charles Darwin, Voyage of the Beagle

This is a guess but I'm thinking that most of the sounds are from cicadas, which sound like miniature chainsaws. These can make bird surveys impossible when they are large numbers of them "singing."   Forests are excellent at sound attenuation and the more dense the forest the faster the attenuation. Higher frequencies are attenuated more efficiently so the buzzing a cicada is quickly dampened by forest vegetation. But.. but in the open... nnnneeeeeeeeeeeeeeeeeeeeee