Sound depends on viewing angle.

When firing with a bow or crossbow straight in the air it makes no sound. The Volume depends on the viewing angle (not the firing angle).

Firing a bow straight down in the ground -> Sound is the loudest. In horizontal line its medium and it vanishes the more you point upwards.

However, its not just bows. General some sounds are very silent when looking straight in the air, for example firing a bunch of arrows with different power so they hit the ground near, medium, and in distance. Now when you move forward to collect the arrows the collecting-sound also depends on the viewing angle... looking upwards while moving forward and you dont hear the "plopp"... same if you drop items on the ground. The volume when collecting them depends also on the viewing angle.