SOXI.EXE, PLAY.EXE, and REC.EXE are not distributed with this package to reduce size requirements. They are, in fact, only copies of the original SOX.EXE binary which changes SOX.EXE's behavior based on the executable's filename.
If you wish to make use of these utils then you can create them yourself.
copy sox.exe soxi.exe
copy sox.exe play.exe
copy sox.exe rec.exe
из недр SOX README.win32.txt