Wave to MP3 to Wave - An Example
Original Wave (unencoded) -- 11025 KHz 8-bit mono, white noise
The file was converted to MP3, then converted "back" to .wav using WinAMP 2.76 (EQ disabled, of course).
This is what MP3 encoding (at 20kbps) did to the waveform. It still sounds almost the same! Higher bitrates (and music instead of white noise) will bring a closer resemblance, but MP3 encoding is not "lossy compression," it's sound modelling.