2012_01_28 birr \bur\, noun: A whirring sound.

birr \bur\, noun:
1. A whirring sound.
2. Emphasis in statement, speech, etc.
3. A whirring sound.
verb:
1. To move with or make a whirring sound.
She pursed her lips and, expertly, imitated the red-winged blackbird's call: not the liquid piping of the wood thrush, which dipped down into the dry tcch tchh tchh of the cricket's birr and up again in delirious, sobbing trills…
 -- Donna Tartt, The Little Friend: A Novel
I turn to the woman. There's a wheezing birr coming from her own bleached-out face.
 -- Irvine Welsh, Filth
Birr is derived from the Icelandic word byrr meaning "favorable wind."