We defined a syllable as a peak of sonority surrounded by less sonorous sounds. In most cases, the peak of sonority, that is, the nucleus of a syllable, is a vowel because vowels are the most sonorous sounds. But in some conditions, a sonorous consonant, a nasal or a liquid, can be the nucleus of a syllable. In those cases, the consonant is transcribed with a special diacritic to indicate its syllabic status.
Do you remember our definition of a syllable from a couple of units ago? We said that a syllable has a nucleus: the peak of sonority, which is surrounded by less sonorous sounds. We already know that vowels are the most sonorous sounds, so most syllables have a vowel as the nucleus. We know that glides are also fairly sonorous, but they’re too short to serve as the nucleus of a syllable. Thinking about all the consonant sounds we know, some of them are more sonorous than others. Stops are not very sonorous because they have so little airflow because the vocal tract is completely obstructed. And fricatives also aren’t very sonorous because of the obstruction in the vocal tract. But nasal consonants are quite sonorous because the airflow resonates through the nasal cavity even when the oral cavity is stopped. And the liquids, [l] and [ɹ], are also quite sonorous because air is allowed to flow around the tongue.
These sonorous consonants can sometimes serve as the nucleus of a syllable in their own right. In other words, there are some syllables that don’t have a vowel at all, just a sonorous consonant. Let’s look at some examples.
In the word rhythm, the second syllable is unstressed, and it’s pretty short. Most of the time, in ordinary rapid speech, that second syllable doesn’t have a vowel in it at all. Our articulators go right from the [ð] sound at the end of the first syllable into the [m] sound. The [m] itself becomes the nucleus of the syllable. It is said to be a syllabic consonant, and we use a special notation to transcribe it: [ɹɪðm̩]. Look at that little vertical line below the [m] symbol — that’s called a diacritic. Diacritics are special additional notations we add to IPA symbols to give extra information about the sounds. That vertical line is the diacritic for a syllabic consonant.
Here’s an example of a liquid consonant becoming syllabic. When we speak the word funnel, we don’t produce a vowel in the second, unstressed syllable. Instead, we pronounce the [l] as a syllabic [l̩], so that it is the nucleus of the syllable. The notation is the same, with the diacritic for the syllabic [l̩]: [fʌnl̩].