As explained in this question, a dash character is used in katakana as an extension of a sound.
First, what exactly is this character called? A "nobasu mark"?
Anyway, I saw this sign in Shibuya the other day:
It's not a remarkable advertisement. It simply says 「ケータイ代{だい}に悩{なや}まない3年間{ねんかん}を。」
, which means something like "Get a three year worry free mobile phone service plan." (Very loose translation.)
What struck me though is that in this case, they are using katakana for a word for which there is kanji: 携帯{けいたい}
, and in that kanji, the first character is read けい
. Not けえ
.
I always thought that the purpose of ー
was to extend the same sound from the previous character. Or, in other words, use the same 段{だん}
, or "vowel row", in the hiragana syllabry. So the ー
in ラーメン
represents あ
because it follows ら
, both in the あ段{だん}
.
Intuitively, of couse I recognize that ケー
is probably more of a phonetic representation than anything rule based.
So, more out of curiousity than anything else, is there any set of rules which determine what exact sound a ー
should be? I feel that as someone who has gained a familiarity with Japanese, I just unquestioningly intuit the reading for ー
when I come across it, but if one were to try and explain it to someone completely new to Japanese, how would you do it?
ー
is called長{ちょう}音{おん}符{ぷ}
(in Unicode it's called the "Katakana-Hiragana Prolonged Sound Mark").