An old-school polyphonic synthesizer
Specialized sound synthesizer with Byzantine Church music scales
Polyphonic synthesizer LV2 plugin
Additive Synthesizer
Phase Modulation Sound Synthesizer
Buzztrax is a modular music composer for Linux
Windows console tone generator,
Text-to-Speech System for Galician and Spanish
Epos is a language independent rule-driven Text-to-Speech (TTS) system
A GPL software synthesizer for all.