This Bluesky thread with Howard Tayler reminded me that, although I posted progress updates about it on Twitter back in the day, I never did a comprehensive write-up on how the thing works.
A good place to start is this Reddit comment on Toki Suli.Yeah, it's not Tjugem, but phonetically it works the same way. Quote:
in the WAV files, the 'm' sounds seem to be going up rather than down, such as with "mi", even though the "m" is supposed to be grave. sharp and acute sounds seem to go down rather than up, such as in "tu".
is the linguistic term for "downward" vs "upward" the opposite of what i'd expect from a western music theory perspective? or am i maybe missing something as i'm listening to the files?
Yes, Reddit user, you were missing something! Because in the phonetics of human whistle registers, "grave" and "acute" are
positions. not
motions. So, if you move from a vowel to a grave consonant, the formant will go down in pitch--from a middle-pitch vowel locus to a low-pitch consonant locus. But when going from a grave consonant to a vowel, pitch will go up--from a low-pitch consonant locus to a middle-pitch vowel locus. An "m" in between two vowels willl be realized by a down-then-up formant motion, while a "t" between two vowels will be realized by an up-then-down motion.
Now, because whistled speech only has a single formant, it turns out to be not-unreasonable to
write whistled speech as an image of the formant path on a spectrogram. You can just write a continuous line with a pen! Or, almost. There are some details--like amplitude variation--that are lost if you try to write with a ballpoint, and still difficult to get right if you write with a wide-tip marker or fountain pen. Thus, a few extra embellishments and decorations are useful, but that is the basic concept: each letter is just the shape that that letter makes on a spectrogram when pronounced. And with just that background, you should be able to start to make sense of this chart of Tjugem letters, as they would be written on lined paper:
The correspondence between Tjugem glyphs and the standard romanization is as follows:
Keep in mind, however, that the actual phonemes are whistles--not sounds that are representable with the IPA, despite the fact that the romanization is designed to be pronounceable "normally" if you really want to. And for the sake of space, only the allographs for one vowel environment are shown for each consonant. The G glyph is not so much a "glyph" as a lack of one, which is why it does not show up in the first image; acoustically, the phoneme is just a reduction in the amplitude of a vowel, represented by a break in the line. Thus, any line termination could be interpreted as a G. That necessitated the introduction of the line termination glyphs, which have no phonetic value but just indicate that a word ends with no phonemic consonant. The above-line vs. below-line variants of the Q glyph are chosen to visually balance what comes before or after them. Additionally, the "schwa" vowel (romanized as "E") is not represented by any specific glyph. The existence of a schwa sound in the first place is an unavoidable artifact of the fact that transitioning between certain consonants requires moving through the vowel space, but which vowel loci end up being hit isn't actually important. So, in the Tjugem script, the schwa just turns into whatever stroke happens to make the simplest connection between adjacent consonants.
You shouldn't be expected to always be writing on lined paper, which explains the extra lines--a mark above or below a vowel segment tells you whether it is a high vowel or a low vowel, for those curves which could be ambiguous. And the circular embellishments help to distinguish manner of articulation for different consonants, which have the same spectral shape but different amplitude curves, which would otherwise have to be indicated by varying darkness or line weight. But note in particular that every consonant comes in a pair of mirror-symmetric glyphs: one moving
from the vowel space
to the consonant locus, and one moving
from the consonant locus
to the vowel space. And there are
three different strokes for each half-consonant depending on
which vowel is next to it! Making for a total of six different strokes for every consonant, because the actual spectral shapes of consonants change depending on their environment! It's allophony directly mirrored in allography.
This makes creating a font for Tjugem rather... complicated. Sure, we could assign every allograph to a different codepoint, but that would be very inconvenient to use. It would be nice if we could just type out a sequence of phonemes, one keystroke per phoneme, and have the font take care of the allographic variation for us! Is that sort of thing possible? Yes! Yes, it is!
The individual letter forms get assigned to a list of display symbols, specifying every possible consonant/vowel pairing:
# i_t i_d i_n i_k i_g i_q i_p i_b i_m
# a_t a_d a_n w_a_k j_a_k a_g w_a_q j_a_q a_p a_b a_m
# u_t u_d u_n u_k u_g u_q u_p u_b u_m
# t_i d_i n_i k_i g_i q_i p_i b_i m_i
# t_a d_a n_a k_a g_a q_a p_a b_a m_a
# t_u d_u n_u k_u g_u q_u p_u b_u m_u
# i_i j_a j_u_a j_u
# u_u w_a w_i_a w_i
and the slots for the romanized letters that we actually type out (a b d e g i j k m n p q t u w) are left blank. Contextual ligatures are then used to replace the sequence of input phonemes with an expanded sequence of intermediate initial, final, and transitional symbols, which are then finally substituted by the appropriate display symbols, which are then used to look up the correct alloglyphs. Then, it we update the boring straight-ruled glyph set with a slanted, more flowy-looking version, we can get a calligraphic font slightly reminiscent of Nastaliq, where lines can overlap each other because the ornamentation disambiguates; the Tjugem Tadpole script:
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