This article describes an adaptive synthesis technique based on frequency (phase) modulation of arbitrary input signals. The background and motivation for the development of the technique, as well as related work, are discussed. A detailed description of delay line-based phase modulation of sinusoidal and complex signals is provided. The basic design of an implementation of the technique is presented and commented. A series of examples using four different instrumental sources are discussed. The results show a wide range of possible effects through the use of the technique, from addition of higher components, to changes in the odd-even harmonic balance and the introduction of controlled inharmonicity.

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The problem of signal synthesis from bilinear time-frequency representations such as the Wigner distribution has been investigated [1,2,4] using methods which exploit an outer-product interpretation of these distributions. The Modal distribution is a timefrequency distribution specifically designed to model the quasiharmonic, multi-sinusoidal, nature of music signals and belongs to the Cohen general class of time-frequency distributions. Existing methods of synthesis from the Modal distribution [3] are based on a sinusoidal-analysis-synthesis procedure using estimates of instantaneous frequency and amplitude values. In this paper we develop an innovative synthesis procedure for the Modal distribution based on the outer-product interpretation of bilinear timefrequency distributions. We also propose a streaming objectoriented implementation of the resynthesis in the SndObj library [6] based on previous work which implemented a streaming implementation of the Modal distribution [7]. The theoretical background to the Modal distribution and to signal synthesis of Wigner distributions is first outlined followed by an explanation of the design and implementation of the Modal distribution synthesis. Suggestions for future extensions to the synthesis procedure are given.

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