Noise upon the sinusoids

Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity´s (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary sample rate of the shimmer and jitter. A harmonic model introduces individual and common irregularity, and adds a correlation control. The model has been implemented in max/msp and used in contemporary music compositions.