Say you want to reduce the size of a talk show mp3 file to maximize the number of mp3 files that you can load on your player. How do you do that? Here is a 'lame' command:
lame -b 40 -m m --resample 22.05 -S KentBeck_Large.mp3 KentBeck.mp3
This reduces the bit rate to 40 kbps (-b 40), sets the mode to mono (-m m), resamples at a frequency of 22.05 kHz (--resample 22.05), and doesn't print anything to the screen (-S). For the 36 megabyte file in this example - this saves 13.75 megabytes - and does not appreciably change the intelligibility of the recording.