Interactive Granular Synthesis of Haptic Contact Sounds
Stephen Barrass, Matt Adcock · 2002
The goal of this project is to automatically synthesise contact sounds that can be easily added to existing and future haptic applications without the need for extensive sound design, sampling or programming. Contact sounds are caused by interactions with objects such as scraping a surface. This continuous information about the surface is much richer than simply triggering a sound sample. In this paper we investigate an “ecological” granular synthesis algorithm that has been used to simulate the sounds of objects made of different materials breaking, bouncing and being scraped. Granular synthesis algorithms can generate a wide range of complex sounds from a pool of sampled grains. We implemented granular synthesis on a Windows PC using the OpenAL API and hardware acceleration on the soundcard to achieve 1000 grains per second. The algorithm was integrated into the Reachin API and rendered from the 1kHz haptics thread with latency between haptics and sound below the 2ms threshold of perception. We developed an initial simple mapping of haptic interaction parameters to the excitement of grains based on tests with four distinct types of haptic surfaces. We found we could hear information such as the force, rate and timing of scraping gestures on the surface as well as properties of the surface such as stiffness, friction, roughness and bumpiness.