So you wish your drone had a powerful speaker for communication through the air? The Drone Megaphone has you covered. It is a 100gram speaker, so your Mavic or Phantom drone should be able to handle it. It has a 800mAh battery and range of 1200 meters.
The speaker has a 600mAh battery and lasts up to 2 hours. It has a sound level of 100dB. You can find out more about it here.