Have a c-oneliner generate something you can directly pipe into /dev/dsp or aplay. For an example (this actually started it) check out this YouTube video.

The code usually follows the basic pattern of

main(t){for(t=0;;++t)putchar(  X  );}

Where X is a formula based on t. You can compile it as follows:

# code in code.c
gcc -xc -lm code.c
./code | aplay

If you don't want to compile it yourself, you can use an online service like http://wurstcaptures.untergrund.net/music/ to render the first few seconds of your track.

You can also compile it inline and have it play directly:

echo "main(t){for(t=0;;++t)putchar(  X  );}"|gcc -xc -lm -&&./a.out|aplay

Note the -lm in both cases which links against the math library so you can use sin, cos, tan, et al.

• add multiple voices using eg. bitwise or „|“
• use operators and bitmasks! +,-,*,/ and &,^,|,«,»
• exploit math functions (sin, cos, tan, …)
• shift left for higher notes „«“
• shift right for lower notes „»“
• add rhythm by shifting everything right by a right-shift of t „(formula)»(t»N)“, the bigger N, the higher the rhythm frequency
• as with everything algorithmically generated: prime numbers are your friend! they make it sound so much more interesting by yielding less repetitive output
• build chords!
  • note 1:

    (t<<6|t<<8)>>(t>>11)

  • note 2:

    (t<<7|t<<11)>>(t>>11)

  • combine:

    (t<<6|t<<8)>>(t>>11)|(t<<7|t<<11)>>(t>>11)