Television playing sound without video

  In computer if we want to hear music but don't want to switch on the monitor we usually switch off the monitor. This reduces the power consumption. Why similar idea is not introduced in television?
  For example if u want to hear only songs which are played in mtv or channel v and don't want to see the video of the song then we can use this idea. For implementing this idea there should be a button in remote controller. By pressing the button the power supply should be there to the television other than picture tube. By this means we can reduce the power consumed.