If I stand at the bottom of a canyon talking with someone standing beside me, my voice will not carry very dar. However, if I stand at the top of that canyon and call out to the people in the valley below, my voice will carry. If I add a couple of loudspeakers and begin to call out to the people below, my voice will carry even father. Everyone in the valley will hear what I have to say. The walls of the valley become acoustic causing the sound to bounce off the walls when I speak. Standing in an ampitheatre, my voice will project far if I stand in the correct place. This is due to position. Our position or location will determine length, strength and echo. The parameters around the call determines the voice of the call.
 
People need to hear a divine sound from Heaven that is clearly recognizable as a sound.