If you have listened to native Japanese speakers, you may have noticed that words like です (desu) often sound like “des” and します (shimasu) sounds like “shimas.” This is because certain vowels in Japanese — specifically the /i/ and /u/ vowels — are often reduced to near-silence between unvoiced consonants, or at the end of utterances. This phenomenon is called vowel devoicing (毫音の無声化, moraon no museika) or, more commonly for learners, silent vowels.
Understanding and producing silent vowels is one of the most important steps to sounding natural in Japanese. This guide explains the rules, gives you plenty of examples, and provides drills to practice.
At a Glance: Japanese Silent Vowels
| Feature | Detail | Note |
|---|---|---|
| Which vowels? | /i/ and /u/ vowels only | The /a/, /e/, /o/ vowels are never devoiced |
| When does it happen? | Between two unvoiced consonants (k, s, t, h, p) | Also at the end of a sentence before a pause |
| Most common examples | です (desu) → “des”, ます (masu) → “mas” | End of polite sentences |
| Register | Natural/casual through formal speech | Happens in all registers, more pronounced casually |
| Listener impact | Native speakers do not notice it consciously | English speakers often pronounce all vowels fully |
| Difficulty level | N4–N3 production skill | Passive recognition earlier; active production with practice |
YukaMy teacher always says です at the end of sentences but it sounds like “des” not “de-su.” Should I pronounce both vowels?
ReiYour teacher is saying it correctly! The /u/ at the end of です is devoiced — it is almost silent. If you say “de-SU” with a full U, it sounds foreign and overly careful. “des” (or a very whispered u) is natural.
The Rule: Which Vowels Go Silent and When
The Two Conditions for Vowel Devoicing
A /i/ or /u/ vowel is devoiced (reduced to near-silence or fully silent) when BOTH of these conditions are met:
- It appears between two unvoiced consonants. Unvoiced consonants in Japanese: k, s, sh, t, ts, ch, h, f, p. (Voiced consonants are: g, z, d, b, n, m, r, y, w.)
- OR it appears at the end of an utterance before a pause (especially in polite verb endings -masu, -desu).
Simple test: if the vowel is sandwiched between two consonants from the unvoiced list, it will likely be devoiced. If either surrounding consonant is voiced, the vowel stays voiced.
Most Common Silent Vowel Examples
| Word | Pronunciation | Rule Applied |
|---|---|---|
| です (desu) | des(u) | Final /u/ is devoiced; /s/ is unvoiced + end pause |
| ます (masu) | mas(u) | Polite verb ending; /u/ silent at end of sentence |
| ですか (desu ka) | des(u) ka | /u/ devoiced; the ka is still pronounced |
| きって (kitte) | k(i)tte | /i/ between k and t (both unvoiced); “ktte” |
| しき (shiki) | sh(i)ki | /i/ between sh and k; “shki” |
| すき (suki) | s(u)ki | /u/ between s and k; “ski” — yes, like the sport! |
| 次 (tsugi) | ts(u)gi — here g is voiced, less devoicing | Partial devoicing; context-dependent |
| 顔 (kao) | kao | /a/ is never devoiced — full pronunciation |
| きます (kimasu) | k(i)mas(u) | Both /i/ after k and final /u/ devoiced |
| すきです (suki desu) | s(u)ki des(u) | Both devoiced: “ski des” |
Unvoiced vs. Voiced Consonants: The Key Reference
| Type | Consonants | Effect on Adjacent /i/ or /u/ | Memory Aid |
|---|---|---|---|
| Unvoiced | k, s, sh, t, ch, ts, h, f, p | These surround the devoiced vowel | かさたはぱ row sounds |
| Voiced | g, z, d, b, n, m, r, y, w, and vowels | These prevent devoicing | がざだば row sounds |
If you are unsure whether a consonant is voiced or unvoiced, try this: touch your throat and say the consonant alone. If you feel a vibration, it is voiced. No vibration = unvoiced.
YukaWhat about すき (suki)? It sounds like “ski” — same as the sport?
ReiExactly! すき (I like) sounds like “ski” to English ears because the /u/ is devoiced between /s/ and /k/ — both unvoiced. This is one of the most famous examples for English speakers to practice.
Words Where Devoicing Does NOT Apply
Not all /i/ and /u/ vowels are devoiced. Here are common exceptions:
| Word | Why No Devoicing | Rule |
|---|---|---|
| ウレシイ (ureshii) | u is NOT devoiced here | u is word-initial; only sandwiched vowels devoice |
| ない (nai) | Full pronunciation | /a/ vowel; never devoiced |
| インターネット (intaanetto) | Inter-NET — n is voiced, so /i/ after n stays | ン before /t/ is an exception case |
| それ (sore) | Full “so-re” | /e/ is never devoiced; /o/ is never devoiced |
| する (suru) | Full “su-ru” | r is a voiced consonant; /u/ stays voiced before /r/ |
| みず (mizu) | Full “mi-zu” | /z/ is voiced; /u/ before /z/ stays voiced |
Practice Drills: Train Your Ear and Mouth
Drill 1: Spot the Silent Vowel
Say each word and identify which vowel (if any) is devoiced:
- した (shita) — under / below / tongue
- きく (kiku) — listen
- てきた (tekita) — was ready / came
- ことし (kotoshi) — this year
- ヒト (hito) — person
Drill 1 Answers
- した (shita) — /i/ devoiced between sh and t. Sounds like “shta.”
- きく (kiku) — /i/ between k and k. Sounds like “kku” or “kku” very fast.
- てきた (tekita) — /i/ devoiced between k and t.
- ことし (kotoshi) — /i/ in shi at end; can be devoiced if followed by silence.
- ヒト (hito) — /i/ between h and t; often devoiced. Sounds like “hto.”
Common Mistakes English Speakers Make with Silent Vowels
| Mistake | Fix |
|---|---|
| Fully pronouncing desu as “de-SU” | Devoice the final /u/: “des.” Practice saying it quietly and quickly. |
| Pronouncing every syllable equally | Japanese mora rhythm is even, but devoiced syllables are whispered, not skipped. |
| Thinking devoicing only affects polite endings | Devoicing happens throughout words mid-sentence, not just -masu/-desu. |
| Confusing devoicing with the silent っ (sokuon / double consonant) | They are different! っ is a full mora pause; devoicing is a whispered vowel. |
Quick Quiz: Japanese Silent Vowels
Answers below.
- Which vowels can be devoiced in Japanese? (a) all vowels (b) only /a/ (c) only /i/ and /u/
- すき (suki = like/love) sounds like which English word? (a) “sew-key” (b) “ski” (c) “soo-ki”
- Why is the /u/ in です (desu) devoiced?
- True or False: A vowel between a voiced consonant (like /z/) is still devoiced.
- きます (kimasu) has how many devoiced vowels? (a) zero (b) one (c) two
Answers
- (c) Only /i/ and /u/ — /a/, /e/, /o/ are never devoiced
- (b) “ski” — /u/ between /s/ and /k/ is devoiced: s(u)ki = “ski”
- The /u/ is at the end of an utterance before a pause, and /s/ (unvoiced) precedes it. Both conditions for devoicing are met.
- False — voiced consonants prevent devoicing. みず (mizu) keeps its /u/ because /z/ is voiced.
- (c) Two — k(i)mas(u): the /i/ after k, and the final /u/ after s, are both devoiced.
Which devoiced word surprised you the most? Try saying すきです as “ski des” and see how natural it feels! Share your practice notes in the comments!
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