According to Wikipedia the Vuvuzela plays a single b-flat tone. If this is transposed down an octave isn't it basically the same frequency of old style Bell System city dial tone (also WECO 355/356 CDO's)? It's almost but not quite the dial tone in some PBX's as well.
Working on the principle that extremely loud sounds of one frequency will actually deafen you to that frequency (by basically wearing out the part of the hearing mechanism in your ear that is sensitive to that frequency), then enough exposure to these horrendous things may prevent you from hearing dial tone!
One hopes that no safety alarms etc use that same frequency as it would be inconvenient to have part of the population insensitive to them.
-- Regards, David.
David Clayton Melbourne, Victoria, Australia. Knowledge is a measure of how many answers you have, intelligence is a measure of how many questions you have.