The study earned Blake a 2006 Ig Nobel Prize. The findings of the study were presented at the Acoustical Society of America conference and support earlier findings from a 1986 study by Vanderbilt psychologist Randolph Blake and two colleagues found that the sound of nails on a chalkboard annoyed people even when the high-pitch frequencies were removed. According to a study run by Michael Oehler, a professor at the University of Cologne, Germany, humans are "predisposed to detest" the sound of nails on a blackboard.
The scratching of fingernails on a blackboard, as well as other pointed, especially metal objects against blackboards, produces a sound that is well known for being extremely irritating to most people. Ghosting occurs when old coloured chalk, pastels or chalkpen ink absorbs into the black finish of the board, making it impossible to remove. Chalk sticks shrink through use, and are notorious for breaking in half unless inserted in a writing utensil designed for chalk. The writing on blackboards is difficult to read in the dark. The dust also precludes the use of chalk in areas shared with dust-sensitive equipment such as computers. Some people find this uncomfortable or may be allergic to it, and according to the American Academy of Allergy, Asthma and Immunology (AAAAI), there are links between chalk dust and allergy and asthma problems. On the other hand, chalk produces dust, the amount depending on the quality of chalk used. Chalk is mostly biodegradable, whereas most plastic recyclers will not take whiteboard markers.Chalk can be easily removed from most clothing whiteboard markers often permanently stain fabric, wood (wood frame), etc.Chalk can be easily erased writing which has been left on a whiteboard for a prolonged period may require a solvent to remove.
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