toggleSound() {
  SoundSet +1, , MUTE
}

turnOnSound() {
  SoundSet 0, , MUTE
}

SoundIsMute() {
  SoundGet, OutputVar, , MUTE
  return OutputVar = "on" ? 1 : 0
}

changeSound(volume) {
  if (SoundIsMute()) {
    turnOnSound()
  }

  SoundSet %volume%
}

;; sound volume control
F10::toggleSound()
F11::changeSound("-5")
F12::changeSound("+5")