Infield Fly?

[buckrog64]

I am not a baseball ump either, (fb and bb) but I witnessed a similar situation this past weekend where there was an IFF called. The bases were loaded and the infield was drawn in, so on the hit they had to retreat a bit to catch the ball, but i thought it was clearly an IFF situation. The base ump signaled IFF, but no one in the stands heard him call it audibly. Do you usually holler IFF? Do you have to yell it loud enough that they hear you in the concession stand? I thought it appeared he handled it properly, but he sure caught hell from the gathered rules experts in the bleachers.