Once you've got your regex that you will be using to determine if a vowel/consonant combo is valid in your dictionary file, I would either pre-compile it using:

my $regex = qr/$string/;

while (my $word = <DICT>) {
   chomp($word);
   if ($word =~ $regex) {
      $yep++;
   }
}
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or use the /o modifier (which assures the compiler that you won't be changing the contents of $string, or at least tells it not to bother recompiling):

while (my $word = <DICT>) {
   chomp($word);
   if ($word =~ /$string/o) {
      $yep++;
   }
}
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so that the regex won't be recompiled each time, as since there are variables in the regex, it forces a recompile, which will slow down your app quite a bit.

Just my two cents.