sough
Sough (verb) means to make a quiet, whispering sound, like wind moving through trees.
Etymology
From Middle English *sough, swough, swogh, from Middle English swoȝen, swowen, from Old English swōgan (“to make a sound; move with noise; rush; roar”), from Proto-West Germanic *swōgan, from Proto-Germanic *swōganą from Proto-Indo-European *sweh₂gʰ-, same source as English echo (via Ancient Greek). Cognate with Scots souch (“sough”), Icelandic súgur (“a rushing sound, rustle”). Noun replaced Middle English swei, sweȝ from Old English swēg. More at swoon.