a syllable. Pitch: in the case of a syllable such as 'cat', the only voiced portion of the syllable is the vowel, so the vowel carries the pitch information. This may relate to the syllable in which it occurs, or to a larger stretch of speech to which an intonation contour belongs. In a word such as 'man', all the segments in the syllable are sonorant and all will participate in any pitch variation. Loudness: this variable has been traditionally associated with linguistic stress, though other factors are usually involved in this. Lehiste (ibid) argues that stress, or loudness, could not be associated with a single segment in a syllable independently of the rest of the syllable (p. 147). This means that vowel loudness is a concomitant of the loudness of the syllable in which it occurs. Length: it is important to distinguish two aspects of vowel length. One is the phonological difference in length exhibited by some languages. Japanese, Finnish, Hungarian, Arabic and Latin have a two-way phonemic contrast between short and long vowels. The Mixe language has a three-way contrast among short, half-long, and long vowels. The other type of length variation in vowels is non-distinctive, and is the result of prosodic variation in speech: vowels tend to be lengthened when in a stressed syllable, or when utterance rate is slow. Monophthongs, diphthongs, triphthongs A vowel sound whose quality does not change throughout the vowel is called a monophthong. Monophthongs are sometimes called "pure" or "stable" vowels. A vowel sound that glides from one quality to another is called a diphthong, and a vowel sound that glides successively through three qualities is a triphthong. All languages have monophthongs and many languages have diphthongs, but triphthongs or vowel sounds with even more target qualities are relatively rare cross-linguistically. English has all three types: the vowel sound in hit is a monophthong , the vowel sound in boy is in most dialects a diphthong , and the vowel sounds of flower, , form a triphthong or disyllable, depending on the dialect. In phonology, diphthongs and triphthongs are distinguished from sequences of monophthongs by whether the vowel sound may be analyzed into distinct phonemes. For example, the vowel sounds in a two-syllable pronunciation of the word flower () phonetically form a disyllabic triphthong but are phonologically a sequence of a diphthong (represented by the letters ) and a monophthong (represented by