I think SoX<-case sensitive. Been a while since I ran an Ubuntu box, but I think it is in the repository/software center. It's command line only, but don't let that scare you. It's pretty simple.
Fellow taper sent me these instructions:
"The basic resampling, dithering and exporting to 16 bit in SoX is pretty
simple. I do it in two steps:
Step 1: sox -S [infile] [outfile] rate -s -v -M 44100
Step 2: sox -S -D [infile] -b 16 [outfile]
The first step resamples to 44.1 khz. SoX dithers by default, but you
can turn that off with the -D switch. I do the dithering during the
resampling instead of during the 16 bit export, not sure which is
better. But I only dither once. -S displays the progress, while -s, -v
and M correspond to very high quality, steep, minimum phase. There's no
separate dithering step without any other conversion, as far as I know.
Step 2 is 24 to 16 bit conversion. Again, -S to show the progress, -D to
turn off dither, -b for bitrate. One thing to make sure is not to have
any spaces in the directory name, the terminal emulator will schitz out.
Also, you can take a look at the different dithering options by typing
sox --help-effect dither. It's a bit more work than r8brain, but as I
said, it's much faster. Hope this helps. If not, let me know."