That's simpler and probably faster than what I had in mind here. Combined with an idea from Discipulus:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $consonants = qr{ [^aeiouAEIOU]+ }xms;
 ;;
 my $s = qq{four score\nand seven\nyears ago\nour fathers\n};
 print qq{>$s<};
 ;;
 open my $fh, '<', \$s or die qq{opening in-memory: $!};
 ;;
 process() while <$fh>;
 ;;
 sub process {
   chomp;
   s{ ($consonants) }{\U$1}xmsg;
   print qq{>$_<};
   }
"
>four score
and seven
years ago
our fathers
<
>FouR SCoRe<
>aND SeVeN<
>YeaRS aGo<
>ouR FaTHeRS<
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