"scratching of fingernails on a blackboard" . "Chalkboard scraping" . "chalkboard scraping" . . "Chalkboard scraping" . "fingernails on a chalkboard" . . . "fingernails on a black board" . "nails-across-the-blackboard" . . "nails on a chalkboard" . "sound of fingernails scraping a chalkboard" .