Using a computer to write data directly into a sound file is very simple, in crude terms WAV files are just sets of numbers (which plot the sounds) admittedly lots of numbers 44100 for just one second... The simplest way is to create these, a program helps! Audacity (free) will allow import of raw data – Project Tab, import raw data. It gives a choice of format, - no worry – CD quality is 16 bit stereo 44100... This enables you to import any files on your computer, and "hear them". I would advise using copy, to copy the file and import this, if you import a program file or WP etc. and mess with the sound and save it- you will 'corrupt' it. So best copy files to a folder, and rename them to be on the safe side! In windows some .exe files have distinctive sound signatures, as do WORD files...
Using this its "fun" to hear what programs sound like, and you can save them as .wav of course. Remember the files need to be big : 44100 samples a second! And once in Audacity you can further process these..
Of course you can create data for sound using such things as segmod, or JAVA et al.. There are plenty of examples out there. You (i've) can experiment with importing data such as PI or Primes... here they are normally text, numbers held as ASCII, Goldwave will import these. PI gives white noise, but there is some structure to the Primes... With movies you can in some cases 'hear' the frames...
You might also try 'recording' with no input, then using Audacity to amplify, you get noise and clicks generated by the CPU etc... Also you can import raw data into photoshop, and "See" rather than hear!!!
Anyway another potential source of material...