Does the run/pass/ball call from the sideline actually help?

Never played defense, do you guys actually hear and react to those calls out on the field?

As a coach, I've noticed you usually have to yell a LOT louder than you think for someone on the field to actually hear you. A lot is going on and the players on the field aren't necessarily listening for you.

I'll keep doing it because it certainly can't hurt to try to call things out for the guys on the field, but like there is no way they hear you right? If you have a bigger team it's probably a different story, but if you don't have numbers on your sideline and the ball is on the far hash it feels like screaming into the void.