After super loud backup alert sound, almost hit a kid today

[Doug Bates]

Neighbors kid who is hard of hearing and wanders a bit had popped out of bushes a few times over the last year and nearly gotten hit by me backing up. It happened again today, nearly had a heart attack today! I'm going to install one of those backup alerts, need something super loud. What I've been searching for is something that allows me to adjust the volume. However I'm coming up empty handed.

Can you help me out please?