Re: encoding phonetic tone letters

From: John Hudson (
Date: Fri Sep 10 1999 - 18:33:07 EDT

At 01:42 PM 10-09-99 -0700, wrote:

> Since we're on the topic of phonetic symbols, I've got an idea
> to throw out for feedback. IPA provides for indicating tones
> using tone letters, but only five are defined in Unicode U+02E5
> - 02E9, which represent five levels. A lot more is needed for
> representing tones, however: if you look at the chart of IPA
> symbols at you'll
> see five contour letters followed by "etc.". I.e. these are
> only a pattern.

> In practice, 5 tone levels cover most situations, but I've
> heard of 7 being needed in some situations. I have also
> encountered contours that are sequences of up to 3 tones long.
> Supposing up to 7 levels and sequences of 1 - 3 in length, the
> possible combinations come to something like 400 in all. Now, I
> don't think any of us are enamoured with the thought of adding
> 400 tone letters to the standard. In place of that, though, 8
> characters for tone letters could be sufficient: 7 to indicate
> tone levels, and 1 to demarcate the begnnings of sequences.
> (Where contours are not involved, the delimiter isn't needed.)
> Given that there are 5 characters already, we'd only be looking
> at 3 more (assuming 7 is really what's needed to cover all
> situations). It would be up to some smart font technology, such
> as AAT or OpenType, to substitute actual contour glyphs for the
> sequences; in the absence of smart fonts, a sequence of level
> tone letters are shown, and the delimiter either appears as a
> small visual delimiter or is zero-width.

Unicode already presumes glyph substitution sequences to handle contour
tones (see Unicode Standard 2.0, section 6, pp. 12-13), and I had to make a
font last year which included glyphs for contour tones. One of the problems
I discovered is that linguists use the tone contours inconsistently, so
GSUB routines for such accessing these glyphs may not exactly correspond to
an individual linguist's application of tone marking for a particular
language. For example, one linguist may employ a falling tone contour to
indicate a greater tone shift than another, from extra high to low rather
than from high to low. These decisions are informed by the nature of the
language being recorded.

Beyond 'pure' IPA phontetic notation, when the letters and conventions of
the IPA alphabet are adapted to orthographies for tonal languages, the
system of tone marking breaks down even further. Tone marking in African
orthographies is wildly inconsistent, with the same diacritic marks
indicating completely different tone levels in different languages and even
within different literary communities of the same language. Add to that the
need in dictionaries and literacy texts to indicate both tone and
nasalisation on the same vowels in some languages, and you have a real
mess. At this point, it becomes impossible to speak meaningfully of a 'high
tone' character, a 'low tone' character, etc. -- let alone of characters
signifying precise shifts in tone -- outside of a particular system with
fixed rules (e.g. Pinyin). This is where it is a relief to simply be able
to say 'This is a circumflex' or 'This is a tilde with a diaeresis above
it': abstracted names for abstracted signs which are expected to signify
different things in different systems.

John Hudson

Tiro Typeworks
Vancouver, BC

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