03/05/2015
Some special syllabograms in both hiragana and katakana reflect allophones in the Japanese language. Allophones are different physical sounds that are perceived as the same sound by speakers of a language. Typically the position of a kana in the grid determines its pronunciation, but these special signs are pronounced differently. For instance, the hiragana sign し is located in the s column and i row, which means it should have the phonetic value of /si/. But instead it is pronounced as /ši/ (like English she) due to linguistic change. As a result, /s/ and /š/ are allophones before the vowel /i/ and perceived as the same consonant in Japanese.
The following are the allophones in Japanese.
In additional to the basic signs, several diacritic marks are used to change the quality of the consonants. Two diagonal dashes placed on the upper right corner of a sign starting with /k/, /s/, or /t/ turns the voiceless consonant into a voiced one. Note that I'm using hiragana for all examples, but the same rules apply to katakana as well.
A special case occurs with the /h/ series, which serves as the basis of bilabial consonants /b/ and /p/. A small circle on the upper right turns the consonant to /p/, where as the double-diagonal-dash mark changes the consonant to /b/. Historically speaking, the /h/ sound in modern Japanese corresponds to the bilabial fricative sound /f/ or /Φ/ in Old Japanese (and still preserved in modern ふ /fu/) which is why the /h/ series came to be the basic signs for bilabial signs.
Another feature of the Japanese language is patalization, which is changing the quality of a consonant to have a /y/-like quality. To write palatalized sounds like /kyo/ in Kyoto, the convention is to use the -i sign with the desired consonant, followed by a sign from the /y/ series. The /y/ sign is written in a smaller size to distinguish it from a fully syllabic sign. When the /y/ sign follows the syllabogram し /ši/, ち /či/, or じ /ji/, then the patalization is dropped and a simple syllable with the regular consonant and a vowel is represented.
It is possible to have a double consonant in Japanese, like /kk/, /ss/, /tt/, and /pp/. The first of the double consonant is always represented using a smaller /tsu/ sign.
And finally, Japanese also has long vowels, such as /aa/, /ee/, /ii/, /oo/, /uu/. The way they are written in hiragana is actually different from the way in katakana. In hiragana, long vowels is indicated by using the syllabogram with the matching vowel from the vowel-only series. So /yuu/ is be written as /yu/ followed by /u/. On the other hand, in katakana, a horizontal line is used for all vowels to mark that it's long.
