Fricative
A fricative, also known as a spirant, is a type of consonant sound in phonetics characterized by the production of turbulent airflow through a narrow constriction in the vocal tract, resulting in audible friction or hissing noise.[1][2] This manner of articulation distinguishes fricatives from other consonants like stops, where airflow is completely blocked, or approximants, where the constriction is wider and less turbulent.[1] Fricatives are classified primarily by their place of articulation—the location in the vocal tract where the constriction occurs—and by voicing, which determines whether the vocal cords vibrate during production (voiced) or not (voiceless).[2] Common places of articulation for fricatives include labiodental (involving the lower lip and upper teeth), dental (tongue against or between the teeth), alveolar (tongue at the alveolar ridge behind the upper teeth), post-alveolar (tongue slightly behind the alveolar ridge), and glottal (at the larynx).[2][1] Across languages, fricatives can occur at up to 11 pulmonic places of articulation, from bilabial to glottal, though not all combinations with voicing are phonemically distinct in every language.[3] In English, there are nine fricative phonemes, forming pairs of voiceless and voiced counterparts at most places of articulation, except for the glottal /h/, which is voiceless.[2] These include: [2] Fricatives play a key role in phonological contrasts, such as minimal pairs in English (e.g., sip vs. zip distinguishing /s/ and /z/), and their acoustic properties, like spectral noise, are crucial for speech perception and analysis.[1]Definition and Articulation
Definition
In phonetics, fricatives are obstruent consonants produced by directing airflow through a narrow constriction in the vocal tract, generating turbulent noise known as frication, without the complete closure characteristic of stops or the smooth airflow of approximants.[4][5] This manner of articulation relies on the articulators—such as the lips, tongue, or teeth—approximating closely enough to create friction but not obstructing the airstream entirely, resulting in a continuous, hissing or buzzing sound.[6] Fricatives are defined primarily by this severe but incomplete constriction, which divides the vocal tract into front and rear cavities that shape the resulting noise, and they form one of the major categories of consonant manners in the International Phonetic Alphabet (IPA).[4] The term "fricative" derives from the Latin fricare ("to rub"), reflecting the frictional turbulence produced; it was first attested in phonetic contexts in the mid-19th century, with Henry Sweet providing a systematic description in his foundational work A Handbook of Phonetics (1877).[7][8] Representative examples include the voiceless labiodental fricative /f/, articulated by pressing the lower lip against the upper teeth to force air through a narrow gap, creating a diffuse friction noise, as in English "fan."[4] Another common instance is the voiceless alveolar sibilant /s/, formed by raising the tongue tip toward the alveolar ridge to channel airflow into a tight stream, producing a high-pitched hiss, as in English "see."[4] Fricatives may also be distinguished by voicing, where the vocal folds vibrate to add periodic pulsing to the friction.[6]Articulatory Mechanism
Fricatives are produced through a partial closure of the vocal tract at a specific place of articulation, where two articulators come close enough to create a narrow channel—typically 1-3 mm in width—through which pulmonic airflow is forced, generating turbulent airflow known as frication.[9] This constriction prevents complete occlusion, distinguishing fricatives from stops, while the degree of narrowing ensures sufficient air velocity to induce turbulence rather than laminar flow.[10] The active articulator, such as the lower lip in labiodental fricatives like or the tongue in coronal fricatives, approaches a passive articulator, including the upper teeth for and [θ] or the alveolar ridge for .[9] In labiodental , the lower lip everts slightly to form a tight seal against the upper incisors, creating a short constricted passage anterior to the teeth.[10] For interdental [θ], the tongue tip or blade positions between the teeth, forming a smooth, open channel without groove. In alveolar , the tongue blade raises to the alveolar ridge, often with a central groove directing airflow toward the incisors.[9] Variations in stricture degree and shape influence the airflow pattern; for instance, postalveolar [ʃ] involves a domed or flat tongue with a grooved configuration that channels air against the palate, enhancing turbulence intensity compared to the smoother stricture in [θ].[9] These configurations divide the vocal tract into anterior and posterior cavities, with the anterior cavity's length and shape varying by place: short for (tongue grooved near teeth) and longer for [ʃ] (airflow along the hard palate).[9] Aerodynamically, the narrowing accelerates airflow, increasing the Reynolds number (a dimensionless measure of inertial to viscous forces, typically exceeding 1800 for turbulence onset), while the Bernoulli effect causes a pressure drop across the constriction, further promoting suction and unstable flow leading to turbulence.[9][10] In voiced fricatives like , this process balances with glottal vibration, requiring precise control of subglottal and intraoral pressures to sustain both frication and voicing.[9]Classification
By Place and Voicing
Fricatives are classified by place of articulation, which specifies the point of constriction in the vocal tract generating the turbulent airflow, and by voicing, which differentiates sounds based on vocal fold activity. The International Phonetic Alphabet (IPA) recognizes eleven primary places for fricatives: bilabial, labiodental, dental, alveolar, postalveolar, retroflex, palatal, velar, uvular, pharyngeal, and glottal.[11] Each place typically supports voiceless and voiced variants, though their presence varies across languages.[12] Voicing in fricatives is determined by the state of the glottis: voiceless fricatives, such as /f/ or /s/, are produced with open vocal folds, yielding aperiodic noise from the constriction alone, while voiced fricatives, such as /v/ or /z/, involve vocal fold vibration, which modulates the airflow with a periodic component and reduces overall intensity due to increased supraglottal pressure.[12] This contrast is phonemic in many languages, enabling distinctions like English "fan" /fæn/ versus "van" /væn/.[13] The following table summarizes common fricatives by place and voicing, with representative IPA symbols and examples from languages where they occur phonemically or allophonically.| Place of Articulation | Voiceless Symbol | Voiced Symbol | Examples |
|---|---|---|---|
| Bilabial | ɸ | β | ɸ: Japanese "fuji" [ɸɯdʒi]; β: Spanish "lava" [ˈlaβa] "wash"[14] |
| Labiodental | f | v | f: English "fin" [fɪn]; v: English "van" [væn][13] |
| Dental | θ | ð | θ: English "thin" [θɪn]; ð: English "this" [ðɪs][13] |
| Alveolar | s | z | s: English "sin" [sɪn]; z: English "zoo" [zu][13] |
| Postalveolar | ʃ | ʒ | ʃ: English "ship" [ʃɪp]; ʒ: English "measure" [ˈmɛʒɚ][15] |
| Retroflex | ʂ | ʐ | ʂ: Mandarin "shī" [ʂɨ]; ʐ: Mandarin "rén" [ʐən][12] |
| Palatal | ç | ʝ | ç: German "ich" [ɪç]; ʝ: Spanish "yo" [ʝo] (in some dialects)[16] |
| Velar | x | ɣ | x: Spanish "jota" [xota]; ɣ: Dutch "goed" [ɣut][15][12] |
| Uvular | χ | ʁ | χ: German "Bach" [bax]; ʁ: French "rue" [ʁy] |
| Pharyngeal | ħ | ʕ | ħ: Arabic "ḥāʾ" [ħa]; ʕ: Arabic "ʿayn" [ʕajn][12] |
| Glottal | h | ɦ | h: English "hat" [hæt]; ɦ: Czech "havěť" [ɦavɛcɲ][13][12] |