Evaluation of Interpolation Strategies for the Morphing of Musical Sound Objects

Audio morphing is a timbre-transformation technique that produces timbres which lie in between those of two or more given tones. It can thus be seen as the interpolation of timbre descriptors or features. Morphing is most convincing when the features are perceptually relevant and the interpolation is perceived to be smooth and linear. Our research aims at producing practical guidelines for morphing musical sound objects. We define a set of features aimed at representing timbre in a quantifiable fashion, as completely and with as little redundancies as possible. We then report the interpolation of each single feature imposed on an otherwise neutral synthetic sound, exploring strategies to obtain smooth-sounding interpolations. Chosen strategies are then evaluated by morphing recorded acoustic instrumental sounds. All of the scripts and the resulting sounds are available through the www to the reader.