Impact on the sensation of consonance by controlling spectral components of simultaneous pitches consisting a chord in sound synthesis using the additive method

In pitched sounds the ratios between frequencies of spectral components remain close to natural numbers. In acoustic instruments these ratios deviate from exact values due to damping or boundary conditions, complicating use of musical systems defining frequency ratios associated with musical intervals. If such system is imposed on the fundamental frequencies of pitches consisting a chord, higher spectral components may deviate noticeably, strengthening or weakening the effects of beating and roughness caused by their proximity, and changing chord characteristics in terms of consonance-dissonance gradation. Unlike acoustic instruments, sound synthesizers can precisely adjust components of generated signal, and use this phenomenon as a controllable timbre effect. For this purpose spectral components of a chord within the range of beating and roughness are modified to gradually strengthen or weaken both phenomena. The study presents the assumptions of the effect and its implementation in a sound synthesizer based on the additive method.