Based on the discussion on overlapping and co-articulatory gestures, the rules for English consonantal allophones are summarized here. Note that these are formal statements describing language behavior rather than prescriptive grammar rules.
- Consonants are longer when at the end of a phrase (e.g., bib, did, don, and nod).
Consonants at the end of a phrase tend to be articulated for a longer duration compared to when they appear in other positions. This lengthening of the consonantal sound provides a clear indication of the phrase boundary, enhancing the listener’s ability to parse the speech correctly. For instance, the consonants in words like “bib,” “did,” “don,” and “nod” are noticeably prolonged when they occur at the end of a phrase.
- Voiceless stops (e.g., p, t, k) are aspirated when they are syllable initial (pip, test, kick).
When voiceless stops such as /p/, /t/, and /k/ appear at the beginning of a syllable, they are typically produced with a burst of air known as aspiration. This aspiration can be heard in words like “pip,” “test,” and “kick,” where the initial voiceless stop is followed by a noticeable puff of air, distinguishing these sounds from their unaspirated counterparts.
- Voiced obstruents (b, d, g, v, ð, z, ʒ) are voiced only when they occur at the end of an utterance or before a voiceless sound.
Voiced obstruents, including /b/, /d/, /g/, /v/, /ð/, /z/, and /ʒ/, maintain their voicing predominantly when they appear at the end of an utterance or directly before a voiceless sound. In other positions, these sounds may lose their voicing, resulting in a partial or complete devoicing that aligns them more closely with voiceless obstruents.
- Voiced stops (b, d, g) and affricate (dʒ) are voiceless when they are syllable initial (except when immediately preceded by a voiced sound – compare a day with this day).
When voiced stops such as /b/, /d/, /g/ and the affricate /dʒ/ occur at the beginning of a syllable, they are typically produced without voicing unless they are preceded by another voiced sound. This phenomenon is evident in the difference between “a day” (where the /d/ in “day” is voiceless) and “this day” (where the /d/ remains voiced due to the preceding voiced sound).
- Voiceless stops (p, t, k) are unaspirated after /s/ in words such as spew, stew, and skew.
Following the /s/ sound, voiceless stops /p/, /t/, and /k/ do not receive the usual aspiration that occurs when these sounds are syllable-initial. Therefore, in words like “spew,” “stew,” and “skew,” the stops are unaspirated, which differentiates them from their aspirated versions in other contexts.
- Voiceless obstruents (p, t, k, tʃ, f, θ, s, ʃ) are longer than their voiced counterparts (b, d, g, dʒ, v, ð, z, ʒ) at the end of a syllable (e.g., cap – cab and back – bag).
When voiceless obstruents such as /p/, /t/, /k/, /tʃ/, /f/, /θ/, /s/, and /ʃ/ occur at the end of a syllable, they tend to be longer in duration compared to their voiced counterparts like /b/, /d/, /g/, /dʒ/, /v/, /ð/, /z/, and /ʒ/. This difference in length helps to distinguish between pairs such as “cap” and “cab” or “back” and “bag.”
- Approximants (w, r, j, l) are at least partially voiceless when they occur after initial voiceless stop sounds (e.g., play, twin, cue).
When approximants such as /w/, /r/, /j/, and /l/ follow an initial voiceless stop like /p/, /t/, or /k/, they often become at least partially voiceless. This is observable in words like “play,” “twin,” and “cue,” where the approximants are not fully voiced due to the preceding voiceless stops.
- The gestures for consecutive stops overlap, so that stops are unexploded when they occur before another stop (e.g., apt and rubbed).
In sequences of consecutive stop consonants, the articulatory gestures overlap, resulting in the first stop being unreleased or unexploded. This means that in words like “apt” and “rubbed,” the first stop does not have a distinct release before the second stop is articulated.
- In many accents of English, syllable final voiceless stops /p, t, k/ are accompanied by an overlapping glottal stop gesture (e.g., tip, pit, kick).
In numerous English accents, syllable-final voiceless stops such as /p/, /t/, and /k/ are produced with an accompanying glottal stop. This overlapping gesture creates a characteristic glottal reinforcement, which can be heard in words like “tip,” “pit,” and “kick.”
- /t/ is replaced by a glottal stop when it occurs before an alveolar nasal (e.g., beaten).
When the /t/ sound appears before an alveolar nasal like /n/, it is often replaced by a glottal stop in many English dialects. This substitution results in a pronunciation change, as seen in the word “beaten,” where the /t/ is glottalized.
- Nasals are syllabic at the end of a word – after an obstruent (e.g., leaden, chasm).
At the end of words, nasals can become syllabic when they follow an obstruent. This means that the nasal sound itself forms a syllable, as in “leaden” and “chasm,” where the final nasal carries the syllabic weight without an accompanying vowel.
- The lateral /l/ is syllabic at the end of a word – a consonant (e.g., paddle, whistle).
Similar to nasals, the lateral /l/ can become syllabic at the end of a word, especially following a consonant. In words like “paddle” and “whistle,” the /l/ takes on a syllabic role, forming the syllable by itself without a vowel.
- An alveolar stop becomes a voiced tap when it occurs between two vowels the second of which is unstressed (winter – winner).
An alveolar stop like /t/ or /d/ is often realized as a voiced tap [ɾ] when it occurs between two vowels, with the second vowel being unstressed. This is exemplified by the pronunciation of “winter” and “winner,” where the medial /t/ or /d/ is tapped.
- An alveolar consonant becomes dental before a dental consonant (e.g., eighth, tenth, wealth).
When an alveolar consonant like /t/ or /d/ is positioned before a dental consonant such as /θ/ or /ð/, it typically shifts to a dental place of articulation. This shift can be heard in words like “eighth,” “tenth,” and “wealth,” where the alveolar sounds are pronounced with a dental quality.
- Alveolar stops are reduced or omitted when between two consonants (/moʊst pIpl/ – /moʊs pIpl/).
Alveolar stops such as /t/ or /d/ are often reduced or even omitted when they occur between two other consonants. For example, in the phrase “most people” (/moʊst pIpl/), the /t/ in “most” can be dropped, resulting in the pronunciation /moʊs pIpl/.
- A homorganic voiceless stop may occur after a nasal before a voiceless fricative followed by an unstressed vowel in the same word (e.g., hearing /t/ in both agency and grievances).
In specific phonetic contexts, a voiceless stop that shares the same place of articulation as a preceding nasal may appear before a voiceless fricative followed by an unstressed vowel. This phenomenon is evident in words like “agency” and “grievances,” where a /t/ sound can be heard after the nasal.
- A consonant is shortened when it is before an identical consonant (e.g., /k/ in cap and kept).
When a consonant appears before an identical consonant, the first consonant is typically shortened. This occurs in sequences like “cap kept,” where the /k/ sound in “cap” is shorter due to the following /k/ in “kept.”
- Velar stops become more frontal before more frontal vowels. (e.g., clap and talc).
Velar stops like /k/ and /g/ shift to a more fronted place of articulation when they precede front vowels. This fronting can be observed in words such as “clap” and “talc,” where the velar stops are articulated more toward the front of the mouth.
- The lateral /l/ is velarized after a vowel or before a consonant at the end of a word.
The lateral /l/ sound becomes velarized, meaning it is pronounced with the back of the tongue raised toward the velum, after a vowel or before a consonant at the end of a word. This velarization is present in words like “paddle” and “milk,” where the /l/ takes on a darker quality.