Here are some rules describing the relative lengths of vowels
and consonants in different situations. These rules are described
in Ladefoged (2001). All of these rules are implemented in
We will start with some rules describing vowel sounds.
- Vowels are longer in open syllables than they are in syllables
that are closed by a voiced consonant, which is longer than vowels
in syllables that are closed by a voiceless consonant.
- Vowels are usually longer in stressed syllables.
- Vowels are longest in monosyllabic words, next longest in
disyllabic words, and shortest in polysyllabic words.
Here are some rules about the lengths of consonants.
- Voiceless consonants are longer than voiced connsonnats.
- Consonants are longer when they come at the end of a word
- A consonant is shortened if it comes immediately before
an identical consonant.
These are called geminate consonants and only occur in English when
they spread across two words as in white teeth
[w ay t t iy th], or in words with two morphemes which
have one of the consonants in each, such as unknown
[ah n n ow n].
Geminate consonants occur more freely in some other languages.
Some examples in Italian are [n o n n ao] meaning
grandfather, and [p a p p a] meaning porridge.