How loud can you Shout?

We're in the middle of nowhere in Thailand and ahead of us are two men shouting into a public phone. 

Seriously, they would have given a vuvuzela a run for its money.  I turned to my husband and said, "They must be Arabs" . As we came up close enough to the two gentlemen to work out where they were from, it turned out they were Arabs. 

After 25 years of observation, the theory with shouting appears to be, 'the louder I shout the more likely it is I'm going to get my own way.  If the person being shouted out does not give me what I want I will shout louder and louder, and louder and louder, in a cresending noise until the other person bows to my wishes'.

At times it's like being sprayed with verbal paint stripper.  And hense the vuvuzela on the phone outside this rural 7-11 coldstore. 

Sure enough, as we walked up to the two men ahead of us we could translate the almost visible wall of screams.  The Bahraini wanted the bank to send him, immediately, now, not tomorrow, not yesterday, but NOW, "arr-baa-a wa kham-seen alf dollar".