Going back to my roots and figuring out simple sound design, I used basic recordings or synthesizer to generate sounds and then manipulated them with a sound editing software.
You can replicate this without needing to record a sound by visiting public source sound libraries from the community such as :
The synthesis route on a computer you'll need
- a sequencer that can host vst plugins (software instruments)
- vst instruments
- vst effects
A nice shareware sequencer vst host which you can pay for if you use it commercially:
Audacity or Reaper could be used to manipulate the sounds - pitch bending them, or changing the volume, or cutting and pasting.
Your mouth is actually a fantastic sound creation tool, you can use it as the basis for sounds and mangle / manipulate the recording using vst plugins and basic editing.
Synthesizer sounds could be generated by messing with instrument settings to create something then save out the sound and edit it - grabbing the parts of it you want. Alternatively, using an 8bit plugin, you could using the sequencer play a sequence of notes and use that as the sound effect too. It really depends on the direction of the sound you want to take.
Anyway, the best way to start is with a sound source of some sort and then use a sound editing tool to mess with it.
Sony Sound Forge has a free 30day trial. i can start very easily in that and use the internal tone generator to create a sinewave and then create all sorts of electronic sfx just with the internal editing tool set.