Sulcalization

لا توجد لغة منطوقة معروفة بتمييزها الصوتي بين حروف العلة المُخدّدة والحروف العادية. ^{[ 4 ]} ومع ذلك، فقد ورد أن بعض متحدثي النطق القياسي (RP) ينطقون حرف العلة /ɒ/ ، الذي يوصف عادةً بأنه مُدوّر ، بشفتين محايدتين أو متباعدتين، ويُكتسب طابعه المميز من خلال "تجويف أو تخديد جسم اللسان". ^{[ 11 ]}

اقترح أحد الباحثين أن حرف العلة في النطق البريطاني القياسي لكلمات مثل bird ، والذي يُكتب عادةً / ɜː / ، هو في الواقع صوت محايد (شوا) محتفظًا بخاصية النطق الأخرمي للحرف الساكن الأصلي. وبناءً على ذلك، يُفسَّر نطق عنصر / ə / في الثنائيات الصوتية المركزية /ɪə̯/ ، /ʊə̯/ ، /ɛə̯/ في كلمات مثل near ، pure ، و scare ، على أنه ناتج عن فقدان خاصية النطق الأخرمي. ^{[ 9 ]} وبالمثل، لوحظ أن الصوت المكافئ / ɝ / في الإنجليزية الأمريكية، والذي يُنطق بالراء ، يكون متأثرًا بشدة بالنطق الأخرمي. ^{[ 8 ]}

The grooved–slit distinction primarily applies to anterior consonants.^[15][16] Unlike the more common definition of sulcalization, which typically refers to a posterior hollowing (in the dorsal region), grooved fricatives involve raising the sides of the tongue to focus the turbulent airstream on the teeth, producing an anterior hollowing (in the coronal region). This results in a more intense sound, typically associated with sibilants.^[14][17] Slit fricatives, with a flatter shape, have a wider and more dispersed airflow channel.^[14]

J. C. Catford observed that the degree of tongue grooving differs between places of articulation as well as between languages; however, no language is known to phonemically contrast fricatives based purely on the presence or absence of tongue grooving.^[18] Nonetheless, linguists sometimes make a phonetic distinction for certain fricative allophones that occur at the same place of articulation as a grooved or slit counterpart.

For example, [t̞] (a lenited allophone of /t/ found in some English dialects) is commonly described as slit, to distinguish it from grooved [s];^[19][20][21] though it has also been noted that additional articulatory factors may go into the distinction between grooved [s] and slit [t̞], such as a difference of apical and laminal articulation.^[22]

Historically, the terms grooved fricative and sibilant have sometimes been used synonymously (and by extension, slit fricative and non-sibilant), though the reality of sibilant shapes is more complex; not all sibilants share this feature, nor is it necessarily unique to sibilants.^[1] For instance, /ʃ/ is widely regarded to be characterized by a convex doming of the tongue rather than a concave grooving,^[23] and therefore has been defined as slit;^[24] conversely, ultrasound imaging has shown /θ/ in English to exhibit grooving similar to /s/, despite being typically regarded as slit.^[25]

It was once proposed for the IPA to include a diacritic to distinguish grooved and slit fricatives,^[24] but the proposal was rejected.^[26] While lacking diacritics for the feature specifically, the extIPA chart includes [θ͇] and [ð͇] to denote slit alveolar fricatives,^[27] which the authors have noted form a contrastive graphical pair with the more commonly seen [s̪] and [z̪], denoting grooved dental fricatives.^[15][b]