Field Placement & the Physics of Sound

Ever start the year with band camp and everything is set up for that first run putting music and drill together and you are just so excited?
Then the drum major counts off, and the field kind-of explodes. The first attempt is a disaster. All the excitement, the anticipation, the hard work... what happened?
I am still surprised to find programs that don't adhere to (and sometimes don't even know) the best practices of field placement and listening responsibilities. Does the director or drum major verbally count off each field rep? Is your metronome (assuming you use one) not at the back of the field? Do you or the director ever frantically start yelling counts at students from the tower when they get lost? This post should help.
Sound, when it is made, travels in every direction at a relatively slow speed. This speed is so slow that by the time the center snare hears the drum major's verbal count-off and plays his entrance, it sounds behind to the drum major/director/audience. Speaking of audience, even though sound travels in every direction, the only direction we care about as a band is the one leading to the audience/judges. For this reason, there is created a "line of sound" beginning from the group furthest away from the audience (battery or metronome) and the origin of the first sound, all the way up to the group nearest the audience (front ensemble) who actually plays last.
Take a look at this super high-tech field placement chart.

If everybody listens back to the origin of sound and plays with it, the line of sound goes directly to the audience together and in time. This is why front ensemble is always supposed to "listen back" and the battery and winds are NEVER supposed to "listen to the front".
So, how do we create the appropriate listening environment before each rep?
Great question.
Let the metronome or the center snare handle the "aural" aspect of the count-off while the drum major still provides the "visual" count-off. This moves the ensembles' eyes to the front and ears to the back, as should be the case. Please note that an entire book could be written on this subject and we are barely scratching the surface here. This is merely an attempt to provide the basics of a very important topic.
Hopefully, with consistent training in these listening responsibilities, you will find that next time the first attempt and others that follow will run a lot smoother.