Sinological phonetic notation

These primary vowel letters are used by those who want symbols for five equally-spaced vowels in formant space.

• ⟨ᴀ⟩ = central [ä]
• ⟨ᴇ⟩ = mid [e̞]
• ⟨ꭥ⟩ = mid [o̞]

These letters, sometimes mistakenly called "apical",[1][2] derive from Karlgren, from a turned ⟨ι⟩ iota.

• ⟨ɿ⟩ = [ɨ]
• ⟨ʅ ⟩ = [ɨ˞]
• ⟨ʮ⟩ = [ʉ]
• ⟨ʯ ⟩ = [ʉ˞]

These consonant letters are featural derivatives of ⟨ɕ⟩ and ⟨ʑ⟩, which often stand for [ʃ] and [ʒ] rather than alveolo-palatal [ɕ] and [ʑ] in the Sinological literature.

• ⟨ȡ⟩ = [dʲ]
• ⟨ȴ⟩ = [ʎ] or [lʲ]
• ⟨ȵ⟩ = [ɲ] or [nʲ]
• ⟨ȶ⟩ = [tʲ]
• ⟨ɕ⟩ = [ɕ] or [ʃ]
• ⟨ʑ⟩ = [ʑ] or [ʒ]

Sinologists tend to use superscript Chao tone numerals rather than the Chao tone letters of the IPA, even though the numerals conflict with their values in other parts of the world. The correspondence is 1 for low pitch and 5 for high; single digits are frequently doubled to prevent confusion with tone numbers, though sometimes a single digit is used with a short vowel and a double digit with a long vowel.

• ⟨¹⟩ or ⟨¹¹⟩ = [˩]
• ⟨²⟩ or ⟨²²⟩ = [˨]
• ⟨³⟩ or ⟨³³⟩ = [˧]
• ⟨⁴⟩ or ⟨⁴⁴⟩ = [˦]
• ⟨⁵⟩ or ⟨⁵⁵⟩ = [˥]