You’d probably never think of sound as strategic, but engineers and developers in a number of industries have discovered that people respond positively to … well, fake sounds. But whether it’s a satisfying clunk of closing a car door, or the reassuring whirr of the dollar bill deposit in a cash machine, these sounds are artificially-manufactured to instill users with audible confidence in their product. HumansInvent.com found five instances of designer intervention to ensure we get exactly the sound experience our minds expect;