There are two conventions for writing Japanese in Roman letters, the government way, and a way that makes sense. Foreigners, the only people who need signs to be written in a Western alphabet, inevitably use the Hepburn system, which uses basically English consonants and Italian vowels.
Japanese has long vowels and short vowels, and, unlike in English, where it doesn’t matter how long you hold the vowel when you pronounce it, they carry different meanings. So this difference needs to be noted. Obasan (with a short a in the middle) means aunt. Obaasan (with a long a in the middle) means grandmother. Obasan is a four-syllable word: o-ba-sa-n (n is syllabic in Japanese, which is irrelevant here). And obaasan is a five-syllable word: o-ba-a-sa-n.
Since vowel length does not affect meaning in English, we commonly ignore the difference when writing Japanese words. We write “arigato” for thank you, when actually, that’s a long o at the end. Tokyo, we think of as a two-syllable word. In Japanese, it’s a four-syllable word, because both o’s are long.
If you want to be precise, and indicate vowel length, there are two conventions for writing Japanese long vowels in English. One is to write a macron over the vowel: Obāsan" for grandmother (as opposed to obasan for aunt.) The other is simply to write the a twice: obaasan.
Japanese has five vowels: a, i, u, e, o (to use the Japanese order). Pronounced more or less as in Italian - or Spanish or German, like English ah, ee, oo, ay, oh. More or less. So long a can be written in English as aa or ā, long i as ii or ī, long u as uu or ū, long e as ee or ē, and long o as oo, or ō.
But here it gets complicated.
Because when English speakers see “oo” they think of the sound in “moon,” it's not surprising they have trouble knowing you're supposed to pronounce koo like coe and not like coo.
So people have come up with a different way of writing long o to make life easier for English-speaking people. Two ways: oh, and ou.
The “oh” way is commonly used in names: Katoh, Endoh, Satoh, etc. (People who know no Japanese are happy with Kato, Endo and Sato, of course, but often Japanese themselves squirm when the vowel length is not indicated, so we have come up with this compromise of writing an h to indicate a long o.)
The other way, to use “ou” is actually no more helpful than writing “oo”, since the vowel combination ou in English can indicate any of six different vowel sounds, as in though, cough, through, house, country, or glamour. So choosing ou for long o was kind of a dumb idea, turns out.
If it weren’t for computers, the four variants for writing Japanese long o in English, ou, oh, oo and ignoring it, would probably go on struggling for dominance till the end of time. But with the computer age, the Roman alphabet (rōmaji, in Japanese) has taken on greater importance in Japanese life and become less closely tied just to things foreign. Even monolingual Japanese speakers themselves now use it every time they type. To get the word minami, for example, you type in “minami,” hit the space key, and the computer gives you choices of characters to choose from. (With minami there’s only one choice.) You then hit enter, and the Chinese character 南 (meaning "south") is written instead of minami.
When you want to type the long o, there is only one way to do it: you type ou.
And that means when you type the names of two coastal towns in Fukushima Prefecture destroyed by the tsunami, Soma and Minami Soma (actually Sōma and Minami Sōma), of 37,796 and 70,895 people respectively, you type in souma and minami souma. If you type in minami souma you will get 南相馬. If you type in minami soma, you will get something else, and not the names of these towns. Just as, as an English speaker, you can ignore the long vowels and write Tokyo, and not Tōkyō, you can write Minami Soma in English instead of Minami Sōma. But if you want to get 東京 for Tokyo, you have to type in toukyou. And if you want to get 南相馬 for Minami Soma you have to type in minamisouma.
I just thought I’d provide a little perspective on your “correction” following this morning’s article, “In Japan’s Danger Zone, the Stranded Await the Merciful,” by Martin Fackler, in which you say
Correction: March 18, 2011
An earlier version of this article misspelled the name of a small port city in Japan in one reference. It is Soma, not Souma.
I understand it’s much better for all the world to read that quick and dirty “correction” instead of putting up with something like, “An earlier version of this article spelled the name of a small port city in Japan according to the Japanese way of writing Japanese in the Latin alphabet: Souma.” We should have used the English way of writing the name of that port city instead: Soma, and ignored the distinction between long and short vowels in Japanese, which many of our readers will no doubt find pedantic.”
But you’re the New York Times.
And in the wretchedness I feel in being unable to help these people, I thought the least I could do was acknowledge how their town was correctly pronounced in their native language.