adobe-fonts / source-sans

Sans serif font family for user interface environments
https://adobe-fonts.github.io/source-sans
SIL Open Font License 1.1
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IPA symbols with tilde overlay #230

Open projectshifter opened 3 years ago

projectshifter commented 3 years ago

An overlaid tilde is used in the IPA to represent velarization or pharyngealization. In many varieties of English, this is the difference between the light [l] sound in leaf and the dark [ɫ] sound in feel. Given that its usage overlaps with that of the superscripts ˠ and ˤ, it is somewhat rare, but it’s still officially part of the IPA.

Unicode proposal N2632 from 2004 made the case that representing phonetic characters with middle tilde using U+0334 COMBINING TILDE OVERLAY is inappropriate, given that the number of symbols that could reasonably take a tilde overlay is relatively small, and that the variations in size, shape and position of the tilde for each base glyph cannot be easily automated. The 11 characters from this proposal were approved for Unicode 4.0: U+1D6C–U+1D76. One more was added in Unicode 13.0: U+AB68 LATIN SMALL LETTER TURNED R WITH MIDDLE TILDE. However, very few fonts support these precomposed characters, and sequences with U+0334 are far more common. For historical reasons, Unicode doesn’t treat these sequences as canonically identical, but in practice, for example, U+0073 U+0334 s̴ is essentially a stand-in for U+1D74 ᵴ.

Here are the glyphs I’m requesting, in both their composed and decomposed forms.

U+1D6C ᵬ U+0062 U+0334 b̴
U+1D6D ᵭ U+0064 U+0334 d̴
U+1D6E ᵮ U+0066 U+0334 f̴
U+1D6F ᵯ U+006D U+0334 m̴
U+1D70 ᵰ U+006E U+0334 n̴
U+1D71 ᵱ U+0070 U+0334 p̴
U+1D72 ᵲ U+0072 U+0334 r̴
U+1D73 ᵳ U+027E U+0334 ɾ̴
U+1D74 ᵴ U+0073 U+0334 s̴
U+1D75 ᵵ U+0074 U+0334 t̴
U+1D76 ᵶ U+007A U+0334 z̴
U+AB68 ꭨ U+0279 U+0334 ɹ̴
N/A U+00F0 U+0334 ð̴

N2632 identifies four more base glyphs that could potentially take a tilde overlay (v ʔ k ð), but the author couldn’t find any evidence for them. I have found several instances of an eth with middle tilde published since then; they are encoded as U+00F0 U+0334. Since most fonts don’t have anchor points for overlaid diacritics, the glyphs shown are probably ad-hoc, but evidence from UCLA’s handwritten field notes suggests that the tilde should go through the ascender rather than the bowl of the eth.

image Duwairi, Hussain al et al. “Las consonantes en español y árabe: un análisis contrastivo para fines didácticos.marcoELE. Revista de Didáctica Español Lengua Extranjera (2014): 2.

image Næss, Unn Gyda. “Gulf Pidgin Arabic”: Individual strategies or a structured variety? A study of some features of the linguistic behaviour of Asian migrants in the Gulf countries. 2008. University of Oslo. Master’s thesis.

imageArabic, Tunisian Spoken.The UCLA Phonetics Lab Archive. 2007. Los Angeles, CA: UCLA Department of Linguistics.

moyogo commented 3 years ago

@projectshifter k̴ , ð̴ and θ̴ are used in Olivier Durand, 2017, “Remarques sur le consonantisme de l’arabe”, in Folia Orientalia, vol. 54, k̴ is also used in Ashraf Hassan, 2020, Stereotyped Representation of the Foreigner in Egyptian Cinema: A Phono-Morpho-Syntactic and Lexical Study and Corpus, itself citing Manfred Woidich, 2006, Das Kairenisch-Arabische: eine Grammatik which also uses it.

ʔ̴ and h̴ appear in Arne Krause, 2018, Transkription Deutsch-Arabischer Diskurse.

v̴ is used, along with ð̴, in http://www.eurasianphonology.info/listview?lang=Tillo+Siirt+Arabic

So that's v̴ ʔ̴ k̴ ð̴ h̴ θ̴ that are not encoded as single characters.

pauldhunt commented 3 years ago

In fact, I added some of these (n, m which cannot easily take an overlay diacritic) to the latest release of the fonts that went live earlier this month. I also added mark positioning for the those letters with tilde overlay in Unicode that I did not add to the font. Will consider adding the missing forms in the next version.

projectshifter commented 3 years ago

@pauldhunt I did see ᵯ ᵰ in the glyph list, but I didn’t realize you had already implemented the tilde overlay on other letters as well.

pauldhunt commented 3 years ago

@projectshifter test it out. Let me know what can be improved.

projectshifter commented 3 years ago

@pauldhunt The spacing could be improved, I think. The tilde on ᵯ ᵰ is too wide, and letters with the combining overlay need a little more space around them, and maybe some kerning pairs with ascenders and stress marks. Other than that, they work really well.

image

pauldhunt commented 3 years ago

@projectshifter thanks for having a look. what makes you say that the tildes on ᵯ & ᵰ are too wide?