Abstract
This article explores the design of an abstract sound synthesis algorithm that integrates random frequency modulation within a parallel feedback comb filter structure, driven by a detuned cosine signal. This input provides several advantages, including adjustable stabilization of the feedback, elongated sustain, and harmonic enhancement through the unsynchronized propagation of the initial impulse into the delay buffers. The filter’s center frequency is modulated by a real-time, parametric stochastic point process, interpolated into the continuous domain and offering independent control over the distributions of the randomization interval, output value, and the overall shape of the modulation signal. By merging the inherently harmonic nature of comb filters’ resonance with textural complexity, the system introduces a perceptual realism—producing organic yet previously unheard sounds—while maintaining relatively simple means of musical control. The algorithm’s implementation is provided as supplementary material, enabling hands-on exploration of its capabilities and unpredictable behaviors. The included sound examples reveal key observations about emergent sonic properties such as (1) subtle stochastic spatialization, (2) balancing the fragile equilibrium of the feedback stability, (3) spectral shaping with the input envelope, and (4) textural qualities encountered around the perceptual thresholds of time and frequency. Finally, the article outlines potential directions for future development, aiming to enhance the synthesizer’s expressive potential and broaden its application as a parametric model for the synthesis of sound textures.
