Sonorants and Resonants: The Science of Continuous Speech Sounds
In the study of phonetics and phonology, speech sounds are categorized by how air moves through the vocal tract. One of the most fundamental categories is the sonorant (also known as a resonant). Unlike sounds that create friction or sudden stops, sonorants are produced with continuous, non-turbulent airflow. This smooth movement of air makes them some of the most common voiced sounds found in the world's languages.
To understand sonorants, it is helpful to contrast them with obstruents. Obstruents, such as stops (/t/), fricatives (/s/), and affricates, involve a constriction or blockage of airflow that creates turbulence. Sonorants, by contrast, allow for a more open and resonant passage of air.
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Key Facts
- Sonorants include vowels, semivowels, nasals, and liquids.
- They are characterized by continuous, non-turbulent airflow.
- Most sonorants are voiced, meaning the vocal cords vibrate during production.
- Voiceless sonorants are rare, appearing in only about 5% of the world's languages.
- In the sonority hierarchy, sonorants rank higher than fricatives and can often form the nucleus of a syllable.
Classification of Sonorant Sounds
Linguists often use the terms "sonorant" and "resonant" to describe these sounds, though some authors use "resonant" for the broad category and restrict "sonorant" specifically to consonants like nasals and liquids. The primary groups include:
Vowels and Semivowels
Vowels are the most prominent sonorants. Semivowels, such as [ j ] and [ w ], function similarly to vowels in their production and resonance.
Nasals and Liquids
Nasals, such as [ m ] and [ n ], involve air escaping through the nose. Liquids include both laterals (like [ l ]) and rhotics (like [ r ]).
| Feature | Sonorants (Resonants) | Obstruents |
|---|---|---|
| Airflow Type | Continuous and non-turbulent | Turbulent or blocked |
| Voicing | Almost always voiced | Frequently voiceless |
| Examples | Vowels, [m], [n], [l], [r], [w] | Stops ([t]), Fricatives ([s]) |
| Syllabic Role | Can form the syllable nucleus | Usually peripheral to the nucleus |
Voiceless Sonorants
While most sonorants are voiced, voiceless sonorants do exist, though they are quite rare. They are often extremely quiet and difficult for even native speakers to distinguish. These sounds are most frequently found in languages around the Pacific Ocean—including Oceania, East Asia, and the Americas—as well as within the Austronesian, Sino-Tibetan, Na-Dene, and Eskimo–Aleut language families.
In languages that possess voiceless sonorants, they almost always exist in a pair with a corresponding voiced sonorant. For example, if a language has the voiceless /ʍ/, it will also have the voiced /w/. Notable European examples include:
- Welsh: Contains a voiceless alveolar trill /r̥/ and voiceless nasals (/m̥/, /n̥/, /ŋ̊/).
- Icelandic: Features a variety of voiceless sounds including [l̥, r̥, m̥, n̥, ɲ̊, ŋ̊, ȷ̊].
- Ancient Greek: Hypothesized to have included voiceless [r̥, l̥, ʍ], which may explain why many English words of Greek origin (like rhetoric) begin with an "rh" spelling.
Glottalized Sonorants
Many languages utilize glottalization—a modification involving the glottis (the part of the larynx containing the vocal cords)—to alter sonorants. This can manifest in several ways:
- Preglottalization: A glottal onset (e.g., [ˀw]).
- Postglottalization: A glottal offset (e.g., [wˀ]).
- Laryngealization: Also known as "creaky voice," where the sound is produced with glottalization for its entire duration (e.g., [w̰]).
Glottalized vowels are among the most common examples of this phenomenon. In consonants, glottalized semivowels (/ˀj/ and /ˀw/) and nasals (/ˀm/, /ˀn/) are common in the Salish, Tsimshianic, and Wakashan language families of the Pacific Northwest, as well as in various African and Southeast Asian language families.
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Linguistic Complexity and Sound Changes
The complexity of sonorant systems varies wildly between languages. For instance, Old Irish possessed one of the most complex systems ever recorded, featuring 16 sonorant phonemes, including a sophisticated contrast between fortis (strong) and lenis (weak) sounds.
Sonorants are also subject to specific sound changes. Voiceless sonorants often undergo revoicing (becoming voiced again) or fortition (strengthening into a fricative). In North American English, a common phenomenon occurs in connected speech where /t/ and /d/ are "flapped" to [ ɾ ] when they follow sonorants like vowels or the syllabic /l/.
Frequently Asked Questions
What is the main difference between a sonorant and an obstruent?
The primary difference lies in airflow. Sonorants are produced with continuous, non-turbulent airflow, whereas obstruents involve a blockage or constriction that creates turbulence or a complete stop in the air.
Are all sonorants voiced?
Most sonorants are voiced, but voiceless sonorants do exist. They are rare, occurring in only about 5% of the world's languages, and are often difficult to hear.
What types of sounds are considered sonorants?
The sonorant category includes vowels, semivowels (like [w] and [j]), nasals (like [m] and [n]), and liquids (like [l] and [r]).
What does it mean when a sonorant is glottalized?
Glottalization means the sound is produced with an additional modification of the glottis. This can happen at the beginning of the sound, at the end, or throughout the entire duration of the sound (often sounding like "creaky voice").
Why do some English words like "rhetoric" have an "rh" spelling?
This is likely due to the influence of Ancient Greek, which is hypothesized to have used a voiceless alveolar trill [r̥] in certain positions, leading to the specific spelling conventions we see in English today.