A yelling language

Let's face it, you can't yell consonants. Hence words that are only differentiated by consonants will be easily confused with each other when you need to yell.

There are probably many better examples, but here are a few I can think of off the top of my head

code, mode

call, tall

lame, tame

A proper yelling language should consist of only vowels, or sounds that you can sustain. I think radio transmissions can be a good guide: variations of amplitude and frequency.  https://en.wikipedia.org/wiki/Yodeling probably utilizes these ideas, and could become a long distance language.