Sýnthesis is notated electroacoustic music. It has resulted from the experiences I have made with the Studies on the notation of electroacoustic music. However, in this piece, mainly sound synthesis is employed. The idea was to explore the processes of ring and amplitude modulation by means of notation. Sound synthesis is complemented by objets trouvés, found field recordings of rain and thunder storm as well as constantly used reverberation and delay effects. The work may be divided into three sections. It starts with short durations and low density, while the panning is static and the dynamic level controlled by means of traditional symbols. The oscillator types are requested in the beginning of the section and do not change. Only quavers are utilised. However, their length is constantly affected by changing the tempo. In the beginning of the second section, new oscillator types are defined. Additionally, larger durations are employed. The character of this section is shaped by sustained glissandi. Additional diagrammatic systems are used to control the envelopes of these sounds. The modulation indices of the amplitude modulated oscillators also constantly shift. Moreover, the panning is no longer fixed. The final section results from the first one, but the tempo is a lot faster. Additionally, the oscillator types change with nearly every articulation, which re-defines the sound-wise character. As in the first sections, the panning as well as the modulation indices are static again.