you can use the sound card's programs, if it does it like creative's blaster aforementioned by ruben and windowsmonopoly's posts... otherwise, google is your answer on getting software..
i'll give you an example of a program i've used previously (sorry, you'd have to google it and download it yourself):
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audacity: freeware, basic wave editor that can also handle .mp3s and .ogg files, record and playback functions, can save files to .aup (its project file), .wav, .mp3 or .ogg. You will need to download the mp3 plugin if you wish to save as .mp3 though.. likewise with the .ogg.
so as an example, you talk into the mic and record into audacity, then go to its effects menu with the bit you want to change the sounds and fiddle around with it till you find your sound effects...
but yeh.. i dont know of any programs (that arn't paid, or freeware) that you can do real time effects.. but they do exist.. so have fun googleing
fyi notes:
-sharpen your voice can be achieved by speeding up the sound, (opposite for low voice), can also be achieved by fiddleing around with the EQ...
-Echo can be achived with delay, and some sort of decay, or with reverb (sometimes people refer to echo as reverb...) but there are usualy echo plugins on most software..
hope it helps
