Alliteration is the repetition of a leading vowel or consonant sound in a phrase. A common example in English is "Peter Piper Picked a Peck of Pickled Peppers". Alliteration can take the form of assonance, the repetition of a vowel, or consonance, the repetition of a consonant, however, unlike a strict definition of alliteration, both assonance and consonance can regularly occur within words as opposed to being limited to the word's initial sound. Some critics hold the opinion that the term "alliteration" applies just as accurately to phonetic repetitions that occur elsewhere than the initial position (first letter), sometimes falling on later syllables, yet retaining alliterative properties due to the form of the example's meter, which, through affecting the syllables stress may mimic the intensity of the initial. Further, the use of differing consonants of similar properties (labials, dentals, etc.) is sometimes considered to be alliterationoun Similarly, phrases such as "Apt alliteration's artful aid" still seems to retain the efficacy of alliteration despite the unique pronunciation of the "a" in each word. This has been attributed by the American writer Fred Newton Scott to the sharing of the attribute of a glottal stop (which he terms the "glottal catch") by virtually every vowel in the English language when it is found in the initial positionoun