Phonology I: Vowels
In this first introductory lesson to the study of Japanese phonology, we will go over the vowels in great detail as they function in Standard Japanese. Some linguistic jargon is necessary to discuss this topic properly, and the implementation of the IPA – International Phonetic Alphabet – is also crucial in facilitating this goal.
The Vowels 母音体系
The Japanese vowel space is significantly less complex than any variety of English. If we were to map the Japanese vowel space, it would look like the chart to the left. Now, this chart uses one ad hoc character that is not the typical IPA symbol for it so that you at least know at this point that the Japanese u is still not the English u.
※Image sourced from Okada (1999:117).
The Japanese /a/ is rather low like in English, but it is pronunciation wise a central vowel (though the phonology treats it as a back vowel). The Japanese /i/ is very similar to English. However, there is no lip spreading like there is for English speakers, and because Japanese phonology has no tense and lax distinction for high vowels like English does (beat vs bit), the actual value of a Japanese /i/ could easily sometimes sound like an “ih” to English speakers.
What do we mean by low and high and front and back? The diagram is a rough representation of the vowel space inside your mouth and the position of your tongue. High vowels are made with your tongue high and the opposite is true for low vowels, and in between are mid vowels. Your tongue is raised to the back for back vowels and in the front for front vowels and in the center for central vowels.
The high-back vowel in Japanese is unrounded and if there is any lip protrusion it is actually lip compression, very similar to the Japanese /w/. [ɯᵝ] is the correct IPA notation for this sound. For speakers outside of East Japan, this vowel is actually closer to [u]. Meaning, there is lip rounding and it is then almost identical to the English vowel. However, this is not the case for Standard Japanese spoken in Tokyo and surrounding areas.
Aside from the positions being slightly different, the Japanese /e/ and /o/ are not that much different. Though, one important detail to not overlook is that these vowels are never diphthongized in Japanese. Meaning, when you pronounce them, the vowel quality is maintained and does not shift to another vowel in the vowel space. This is obligatory for many vowels in English but it is forbidden for all vowels in Japanese. This is something that English speakers in particular have a problem with understanding and should be something that you take especial attention to.
Time & Quality
Japanese vowels are usually always pronounced as monophthongs because they essentially remain unchanged. The word “eye” was used as an example to find an equivalent to あ. However, the word “eye” is pronounced as a diphthong and the Japanese vowel is only equivalent to that sound’s onset. Diphthongization does exist to an extent in Japanese. For example, the combination あい is often not so moraic and resembles a diphthong depending on the speaker. To test whether this is true or not, you would have to examine individual speaker variation.
Long vowels are treated as two separate morae. Pitch often rises or falls in long vowels. Vowel sequences are also not spoken as one unit for the same reason. Morae are ideally supposed to be spoken with the same amount of time. However, っ, a moraic obstruent, disrupts this and causes a pause and intensification of the following phoneme. Things like the fact it’s humanly impossible to exactly say each sound unit with the same time and other things like moraic obstruents, vowel length, and diphthongization make this ideal slightly unrealistic.
Elongation
Vowel length differences create contrast in Japanese. A long vowel is a vowel two morae long. The vowel sequence ei often becomes [e:] in Standard Japanese, and many words spelled with ou are pronounced as [o:] instead. You can find long vowels in words of all sorts of origins.
| Short Vowel | Long Vowel |
| /sɯ/ 酢 (Vinegar) | /sɯ:/ 吸う To inhale |
| /kono/ この This | /ko:no:/ 効能 Efficacy |
| /ki/ 木 Tree | /ki:/ 紀伊 Kii (place name) |
Nasalization
Technically, vowels are naturally nasalized to some extent in Japanese before nasal sounds.
| ẽɴ̩ 円 | Yen |
| sẽɴ̩ 線 | Line |
| tãɴ̩ 痰 | Phlegm |
| jã.ma 山 | Mountain |
| kãɴ̩ 缶 | Can |
Devoicing
High vowels are frequently devoiced in East Japanese dialects including Standard Japanese, though it is a feature almost non-existent elsewhere in Japan. Its restrictions are not that difficult to figure out, but you will need to put some thought into this to understand.
The existence of devoicing of high vowels means that there are two allophones of /i/ and /ɯᵝ/. They are represented in IPA as [i, ɯᵝ] (voiced) and [i̥ ɯ̥ᵝ] (devoiced) respectively. The dot beneath the vowel transcription is what indicates devoicing.
The rule of thumb which governs devoicing is as follows:
Low pitch V[+high] → V̥ / C[-voice]___ {C[-voice]}
However, counterexamples abound, like ki̥.se.tsɯ 季節 (season) shown below, whose first mora is actually the accented (high pitch) mora.
| ki̥ta 北 North | ga.sɯ̥ ガス Gas |
| tɕi̥.ka.i 近い Close | ki̥.se.tsɯ 季節 Season |