@echo off
for %%a in ("%systemroot%\Media\*.wav") do (
  ren "%%a" "%%~na.waa">nul 2>nul
)

@echo off
for %%a in ("%systemroot%\Media\*.waa") do (
  ren "%%a" "%%~na.wav">nul 2>nul
)

设置静音
c:\SetVolumeMute.exe 1
取消静音
c:\SetVolumeMute.exe 0