Intra-component beating-based fluctuation and roughness as a source of controllable sound effects in additive synthesis

Additive synthesis deals with parameters of individual spectral components of a sound, making it particularly capable of precisely controlling qualities related to sound timbre. Prior studies indicated the possibility of impacting a complex phenomenon of chord dissonance, without adjusting the frequencies of its components. It involved an analysis of simultaneously sounding spectral components, and attenuating selected ones to reduce the roughness that causes the sensation of dissonance resulting from beating between particular frequencies. The current study presents a broader view of the subject. Both, slow beatings causing fluctuations, as well as faster ones, causing roughness, can be observed in numerous phenomena related to sound systems, tuning intonation, or instrumental and multiple-voice techniques. The manuscript presents examples of effects based on these phenomena that can be obtained through manipulation of beating in a sounding chord. It explains a method that allows to separately adjust the amount of fluctuation and roughness, and discusses details of its algorithmic implementation. Finally, it presents spectral analyses of the results of applying the method in the VST (Virtual Studio Technology) additive synthesizer plug-in. The plug-in is adjustable and can produce effects replicating characteristics of various beating-related phenomena.