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This answer uses the say command with the Bells voice. An iTunes solution is not shown here, but it is something you may want to try on your own to get authentic sounding chimes.
-- Big Ben!
set theTime to time string of (current date)
set theHour to first word of theTime as integer
set theMinutes to second word of theTime as integer
set theHour to 3
set theMinutes to 45
-- Get the hour
if theHour is 0 then
set theHour to 12
else if theHour is greater than 12 then
set theHour to theHour - 12
end if
set theChime to theMinutes div 15
if theChime is 0 then set theChime to 4