Glossary of Thai Tonal Terms
A comprehensive guide to phonetic, orthographic, and linguistic terminology
This glossary synthesizes the phonetic, orthographic, historical, and pedagogical terminology found in Thai linguistic research. It is designed to assist learners in understanding the technical aspects of the Thai tonal system.
The Five Lexical Tones (Standard Thai)
- Mid Tone (Siang Saman)
- The most frequently occurring tone in Thai. While traditionally described as a flat pitch, modern analysis shows it often starts in the middle of a speaker's range and falls slightly toward the end.
- Low Tone (Siang Ek)
- A tone that begins low and gradually falls to the bottom of the speaker's vocal range. Acoustically distinct from the Mid tone because it reaches a lower pitch endpoint.
- Falling Tone (Siang Tho)
- A dynamic tone characterized by a "convex" shape: the pitch rises slightly or stays high before making a sharp, sudden drop. In sentence-final positions, this fall is often more pronounced.
- High Tone (Siang Tri)
- A tone that has undergone significant change in modern Bangkok speech. While formerly described as a high, flat pitch, younger speakers now pronounce it with a concave shape—a distinct dip followed by a sharp rise.
- Rising Tone (Siang Chattawa)
- A dynamic tone that dips low before rising sharply at the end. Among younger speakers, this tone is often accompanied by "creaky voice" (a rough or vibrating vocal quality).
Acoustics and Speech Mechanics
- Adaptive Scaling
- The ability of Thai speakers to maintain the correct shape of a tone even when speaking very fast. Instead of cutting the tone short, speakers increase the velocity of their pitch change.
- Concave vs. Convex
- Terms used to describe the curve of a sound wave:
- Concave: A shape that dips down then goes up (valley). The modern High and Rising tones are concave.
- Convex: A shape that arches up then goes down (hill). The Falling tone is convex.
- Fundamental Frequency (f0)
- The scientific measurement of how fast the vocal cords vibrate, perceived by the ear as "pitch". Thai listeners track the movement of f0 to distinguish words.
- Global Lowering
- A phenomenon where tones at the end of a sentence are pronounced with a lower pitch overall compared to mid-sentence, caused by a "low boundary tone" (L%) signaling statement end.
- Peak Alignment
- The specific timing of the highest pitch point within a word. The Falling tone has an early peak (start of syllable), while the High tone has a late peak (end of syllable).
- Tonal Coarticulation
- The influence of one tone on its neighbor. "Anticipatory dissimilation" occurs when a speaker adjusts the pitch of a current word to contrast with the tone of the next word.
- Truncation
- A debated concept referring to whether a tone is "cut off" in fast speech. Recent evidence suggests Thai tones are rarely actually truncated; instead, the movements are compressed or retimed.
Thai Orthography (Writing System)
- Consonant Classes
- The division of Thai letters into High, Mid, and Low groups. This system is a "fossilized" record of historical sounds (voicing) from centuries ago. The class of the consonant helps determine the spoken tone of the word.
Example: Mid-class consonants act as "bridges" and are the most regular, following tone marks exactly.
- Dead Syllable (Kham Tai)
- A syllable that ends abruptly, either with a short vowel or a "stop" consonant (k, p, t). These syllables have restricted tonal options; they cannot naturally carry a Rising or Mid tone.
- Live Syllable (Kham Pen)
- A syllable that ends with a "humming" sound (long vowel or nasal consonants like m, n, ng). These syllables can carry any of the five tones.
- Tone Marks (Wannayuk)
- Four diacritics placed above consonants to alter the tone: mai ek, mai tho, mai tri, and mai chattawa. Their effect changes based on the class of the consonant below them.
Example: mai ek creates a Low tone on a Mid class letter, but a Falling tone on a Low class letter.
Testing, Teaching, and Research
- CU-TFL
- Chulalongkorn University Proficiency Test of Thai as a Foreign Language: The standardized exam for non-native speakers, assessing Listening, Reading, Writing, and Speaking. Rates proficiency from Novice to Distinguished.
- InterBEST
- A massive database (corpus) of 9 million Thai words used by researchers to analyze which words and tones are most statistically frequent in daily life.
- Minimal Pair Approach
- A teaching method from speech therapy where students practice two words that differ only by tone (e.g., khao rising vs. khao falling). Proven to help the brain tune into pitch differences.
- Tone Sandhi
- A rule where a tone changes based on the tone next to it (common in Chinese). Research confirms this is generally absent in Standard Thai; Thai tones retain their identity even when strung together.
Historical and Regional Context
- Great Tone Split
- A historical event (post-13th century) where the original three tones of the Proto-Tai language split into the modern five (or more) tones. Caused by the loss of distinction between voiced and voiceless consonants.
- Pitch-Accent Language
- A description often applied to Southern Thai, which can have up to seven tones and follows different rules than Standard (Central) Thai.
- Standard Thai
- The official dialect based on the speech of Bangkok, used in media, education, and the CU-TFL exam. Distinct from regional dialects like Isan or Northern Thai.