16 kbps 4.5 kHzshortwave radio
32 kbps 7.5 kHzAM radio
96 kbps 11 kHzFM radio
128 kbps 16 kHz near CD
160-180 kbps (variable bitrate) 20 kHzperceptual transparency
256 kbps 22 kHz vstudio
Hi Matt
when you record the audio from say wma or aiff format to mp3, you specify the sampling rate for the conversion.Obviously the higher the sampling rate the bigger the file.
MP3 are thus compressed audio files, so to expect a zip program to make the files a lot smaller is problematic. The table above gives and idea of the quality expected for different sampling rates.
I cant recomend a specific program because I have not had a reason to look for a specific one that resamples mp3.
I use one that converts wma to mp3.
Search using keywords like mp3 to mp3 or mp3 resampler.
