I am looking for a sound synthesizer program for sound effects. Does anybody know of a free sound effects program? I have looked all over the internet but haven’t found any good programs. Any help?
For maximum flexibility, look into PureData, a dataflow programming environment with strong sound-synthesis features. It’s the open source equivalent to Max/MSP; the learning curve is pretty steep if you’ve never done low-level audio before, but the tutorials are great. There’s also a free ebook by Miller Puckette, the researcher/musician who invented it, which explains a lot of ways to make cool sounds. It’s electronic-music focused, but you can get neat effects out of it too.
If you’re looking for samples rather than to synthesize your own noises, The Sound Dogs sells a lot of sound effects, which you could either plug into a sampler to create new sounds, or use straight up in something like Audacity/Ardour.
If you’re serious, you could also invest in a decent digital audio recorder and start making your own samples, for use either in synthesis or just mixing in with a DAW.