protected function _getRandomWord(array $words, $startingLetter = null)
    {
        $wordsToSearch = $startingLetter === null ? $words : preg_grep("/^{$startingLetter}/", $words);
        return $this->_randomizer ? $this->_randomizer->getArrayValue($wordsToSearch) : $wordsToSearch[array_rand($wordsToSearch)];
    }