More often than not described as the last exhale of breathe, heard from the vibration of the neck when it is in an unusual position, allowing air to escape a narrow passage from the throat. It causes any of infinite odd sounds of expulsion of air.
You can imitate a death rattle for fun. Lean your neck backwards at 90 degrees and Pronounce terms such as "Ughrghrghrghrgh" or "Phhztttttt"
a sound produced by a person immediately preceding death, resulting from the passage of air through the mucus in the throat.
He gave a death rattle and then died.
that annoying/scary noise made by the girl in "The Grudge
". this is caused by her neck being broken. Sort of a strangled ahhhhhhhhh.
I heard the death rattle behind me. Then I was dead.