There is one celebrated sound which seems to epitomize the interface dilemma which I have been describing: the sound of chalk or fingernails on slate. We have shown that it is an international sound phobia. Yet physical analysis fails to reveal why it should send cold shivers up the spine. It is not extraordinarily high or loud. It is not accompanied by any hurtful action. It does not even designate anything in particular. No single discipline then is capable of accounting for its remarkable effect. When sound enigmas like this are explained—and not until then—we will know that the missing interfaces are at last falling into place.

Schafer, Murray R, The Soundscape- Our Sonic E…, loc. 496