Pitch accent is the Japanese phenomenon where each mora of a word can have either high or low pitch. In newsgroup discussions, these are represented by a string of letters H or L for high or low.
There are two basic patterns in standard Japanese.
Minimal pair examples
| Rising | Rising and falling | |
|---|---|---|
| Rising and falling | Falling | |
| hashi edge | hashi bridge | hashi chopsticks |
| Word | Accent on first mora | Accent on second mora | Accentless | ||||||
|---|---|---|---|---|---|---|---|---|---|
| hashi | {{pitch|ha|shi}} | 箸 | chopsticks | {{pitch|hashi|}} | 橋 | bridge | {{pitch|hashi|X}} | 端 | edge |
| ima | {{pitch|i|ma}} | 今 | now | {{pitch|ima|}} | 居間 | living room | |||
| kaki | {{pitch|ka|ki}} | 牡蠣 | oyster | {{pitch|kaki|}} | 垣 | fence | {{pitch|kaki|X}} | 柿 | persimmon |
| sake | {{pitch|sa|ke}} | 鮭 | salmon | {{pitch|sake|X}} | 酒 | alcohol, sake | |||
| nihon | {{pitch|ni|hon}} | 二本 | two sticks of | {{pitch|niho|n}} | 日本 | Japan |
Phonetically speaking, the sense that a given mora occurs on one pitch and another mora on a different pitch, is by-and-large an illusion. Pitch makes contours over words and phrases, and there are no instantaneous rises or drops.
Phonemically speaking, probably all dialects (even those that don't have word accent at all) can probably be described in terms of two pitches, high and low. "Low", however, has two allophones--depending on where a low occurs, it may be more or less low (compared to a high or a low in another environment). This led linguists to a sandankan "three step view/theory" of Tokyo-style accent.
The "LH" stuff that appears in sci.lang.japan so often is both potentially ambiguous and overkill. The best way to mark Tokyo-style accent would be with an accent mark on the vowel that precedes (actually, "begins") a drop in pitch. Accent marks in the newsgroup, however, turn to Japanese characters on many people's screens, so the next best thing is probably to put "|" after the last high vowel. (Note this does not work for Kyoto-style accent, which is, so-to-speak, two dimensional.)
:I know the difference between HAshi and haSHI (and 'haSHI GA', for that matter,) but how important is some level of skill with pitch accent? Will I be totally misunderstood, or just easily identified as a gaijin (assuming I'm talking over a phone or intercom?)
Hard to say. Probably not all that important, although there are anecdotes about people from one part of the country being misunderstood in amusing ways in another part of the country. Certainly in Tokyo, native Japanese from all over the country manage to get along without changing their accent. One would suppose that just about everything would be expected, let alone tolerated, from people who don't look like they might be native Japanese.
On the other hand, I have been corrected over and over again during my attempts to speak Japanese, and not only by my wife (who is often wrong, anyway). Sometimes it's because I was misunderstood, like once I called a kettle a turtle (ka|me instead of kame|) in a context where "turtle" might have almost made sense (as is pretty well known in this NG, my Japanese is of the sort that "almost makes sense" anyway). Sometimes it was just because a cranky person wanted to complain, I think.