These represent the number of pieces of plastic put in the ocean every hour. Jordan's piece is meant to make viewers think about their plastic consumption, and how this affects the world at large. By showing how much plastic enters the ocean (merely per hour), this ecological problem becomes tangible and personal, and hopefully effects change.
If you’re talking only about a standard-tuned 6-string guitar played without any extended techniques, then the lowest pitch is E2, and the highest (depending on the model) is about B5.
