Software packages developed for visualising time-varying timbres, findingparameter settings for modelling acoustic instrument tones, and forsynthesising timbres are described. The sndan package, written in C for Unix machines, provides spectrum analysis, pitch tracking, spectrumdisplay, parameter modification, and additive synthesis. Other programsthat estimate the best possible parameters for recreating acoustic soundsusing techniques such as multiple FM and wavetable synthesis and extendednonlinear/filter synthesis are outlined. Hybrid instruments created byfashioning sounds out of the recombined spectral characteristics of two ormore very different tones are also presented.