Scraping sounds and disgusting noises

Thirty-four horrible sounds have been examined in an Internet-based psychoacoustic experiment. This paper presents the results for the scraping and disgusting noises used. It is not understood why some humans find certain scraping noises, such as the sound of fingernails being scraped down a blackboard, so terrible. In this experiment, the variations in ratings with age, gender and location are examined. The results for one of the scraping sounds is consistent with the hypothesis suggested by others, that the response comes from a vestigial reflex related to the warning cries of monkeys. But this was not true for the actual recording of the fingernails scraping down a blackboard. An alternative hypothesis that the response is related to an audio–haptic interaction was tested and results indicated that this idea warrants further investigation. Other possible causes of the response, drawing on work concerning dissonance, are tentatively suggested. The disgusting sounds examined included the worst sound found in the experiment, the sound of someone vomiting. However, none of the disgusting sounds tested promoted responses consistent with a ‘disgust reaction’ based purely on survival instincts. Cultural factors might be important in our response to the disgusting sounds, with the influence of manners and etiquette being suggested as a possible factor.