People can hear a lot of information about an object by tapping and scratching it. We have developed a TapAndScratch node that automatically synthesises the sounds of tapping and scratching interactions with haptic objects in the Reachin haptic API.
The scratching sounds are produced by a granular synthesis algorithm that is used to provide information about interactions with the surface of an object, such as variation in force, rate of scratching and duration of scratch strokes. The scratching sounds can also provide information about properties of the surface such as stiffness, friction, and bumpiness. The tapping sounds are produced by a modal synthesis algorithm that provides more global information about the material and shape of the object when it is tapped. We believe these continuously varying sounds can provide useful information and further engage the user.
Barrass S. and Adcock M (2002) Interactive Granular Synthesis of Haptic Contact Sounds, AES 22nd International Conference on Virtual Synthetic and Entertainment Audio Helsinki University of Technology Espoo Finland 15th17th June (2002).