The approximate pitch difference between the tonemes when realised on the same or different registers is illustrated in Figure 24 below.
As can be expected, when two identical tonemes are placed adjacent to one another they merge in response to the Obligatory Contour Principle (OCP).
Tonemes are pitch-glides on certain syllables or from one syllable to the next in spoken language.
A striking characteristic of spoken Danish is the distinctive "st[??]d" (often referred to as a glottal stop), a feature which is supposed to have developed as a replacement for tonemes. This distinctive feature differentiates the meaning between two words that are otherwise the same in pronunciation; the meaning of these words is indicated by the presence or absence of the "st[??]d." An example of this would be the words <far> (father) and <far!> (the imperative form of the verb <fare> (go!)); the first word does not utilize the "st[??]d" but the second does.
While there is no need to indicate the tonemes or "st[??]d" in an IPA translation, word stress is marked.
Tonemes are secondary in both Sinitic and Finnic languages.
Based on etymological equivalents between Vietnamese and its neighbouring languages, Haudricourt (1954; 1961) established that Vietnamese tonemes originate in earlier consonantal contrasts, and suggested similar mechanisms for Chinese.
In summary, the fundamental tonemes are traces of affixes:
Some actual etyma of the same root contain different fundamental tonemes, since different morphophonological affixes have been formerly added to the same root.
The binary further tonemes and (..2) arose when consonant voicing was lost in the morphophonological C1 position.
Tonemes are often identical in Sino-Finnic shared etyma.
Caveats: Since the fundamental tonemes are secondary and originate in morphophonological affixes, it is difficult to say whether the identical tonemes on both sides have identically survived from the antiquity, or whether they have been coincidentally added to both Sinitic and Finnic.