Why is the difference between おお, おう and おー so important?

Yeah, I think that’s a good way of looking at it. Writing is just a way of representing the language, and for japanese the most fundamental way of representing the language is hiragana and maybe katakana. Kanji are pretty all over the place and don’t have much weight to them. People just use them as much or as little as they want, how they want, as they see fit to get across their meaning and improve readability.

Here’s a funny example leebo sent me to kinda show how fast and loose you can play with kanji

See, that’s the thing, if the meaning is (as far as I can tell) the exact same, and it can be expressed with the same symbols, I would consider it the same word, just with different acceptable readings.
The same would not apply for 人気, since the meanings are different. I only consider it / them (functionally) the same word because they also share their meaning.

I think it’s just a matter of semantics and whether you’d consider 明日 to be one word with one meaning and three different acceptable readings, or if you’d consider あした, あす, and みょうにち to be three separate words that share their meaning and all of which can be expressed with the same kanji.
I am fully aware that the same kanji combinations can be used to convey different words.

Thats the thing, I think many natives would disagree. They would say that あす either feels more formal or that it can also be used to mean the near future and not necessarily tomorrow. And they would also probably say that みょうにち is the more polite version of あす. In fact, I just looked it up and the very first thing that popped up on google was

「明日(あした)」が一般的な語で、「明日(あす)」は、やや改まった言い方。 「明日(みょうにち)」は、さらに改まった言い方

So I know I’m not crazy

Isn’t that information in the daijisen the 歴史的仮名遣い for the word, not an alternate acceptable modern spelling? If you look up 声 I’d expect to find it using that format to tell you the old spelling is こゑ, for example.

Ah, it might be actually now that you mention it. I didn’t check any other words and I’m not on my laptop anymore

Huh, well I’ll have to agree that they’re different, then.
That’s on me for having too much faith in the one place I checked and what I heard from other people without properly double-checking.
My bad.

Precisely (or exactly - just to use an example in English of two words that mean the same thing :slight_smile:). There are lots of scenarios where 2, or more, words have the same meaning, but the nuance and context in which they are used differs. While in pretty much all cases they could be interchangeable, most situations where they are used has a “right” and “wrong” choice which native speakers can generally only explain with “it just sounds right/wrong” or “that is just the way it is”. Not being a trained English teacher, I run into this all the time when helping out my wife, friends or co-workers. I can tell them which one is the correct one, but I cannot explain why, beyond “sounds right” or “the way it is”.

In English, big and large is a common example. They both mean the same thing, but the nuance can differ and the context determines which one is “right”. One source describes it:

Both of these words are used to describe the size or amount of something. However, ‘large’ is more formal and we mainly use it to refer to amounts whereas, ‘big’ is mostly used to indicate the size of an object and the the importance of an issue.

In terms of the importance of the differences that started the thread, I would argue in the opposite direction. That when it comes to learning and using a new language, it is just these sorts of things that it is important to learn and know if one ever wants to speak anything close to fluently/naturally. Which I will likely never achieve, but I keep at it.

Somebody already pointed out this is pitch accent. But, its also important to note that pretty much everywhere in Japan has a different pitch accent. Osaka and Tokyo are literally opposite. Most of Kyushuu doesn’t even have this. Its just flat or even sing songy. Etc etc. Its only important because you are foreign and if you don’t use 標準語 pronunciation than most Japanese outside of the region pitch you use will just assume you are making mistakes.

On the contrary, if a kanasi person is in Tokyo they might think “Whats that accent… oh! Kansai” and be fine. Or “OH! Thats a Fukuoka accent with some of the grammar! Neat!” But, if a foreigner does it… 90% of them will be like “THat dude doesn’t know how to talk”. Unless, you preamble it with you learned your japanese in such and such region. Than, and only than, do they go ohhh its a regional difference.

Interesting, though after working here for a long time, having something marked wrong doesn’t necessarily mean its wrong just not the way they want it to be. They mark plenty of things wrong in English class that are correct, and sometimes even better, than what they expect or want.
I have had to instruct students to dumb down their English in order to pass the Eiken level 2. LIke, what you said IS BETTER. BUT, they want you to say this…

Japan is a silly place.

I would say, that its more formality levels than different meanings. When you click those types of links thats usually what they explain. It means more or less the same thing… but one if for spoken, one is for writing, and one is extremely formal writing (college/graduate school/textbooks).

This is not a hard rule but its what the difference is alot of the time.
ITs why you have to check anytime you run into something like that.

When you start studying for the N1 or when you pass the N1 you’ll discover a lot of the words are like that. If you used them while speaking people would think you’re an odd ball (Or really smart or full of yourself or… you know people they have lots of different interpretations of other people).

But, not always.

The foreigners that do it tend to not do it with any consistency though. They’ll say the first word in the sentence with hyoujungo pitch, the second with kansai pitch, the third with a pitch is wrong in every region, and the fourth with a pitch accent pattern that can’t even exist in Japanese while messing up the vowel lengths.

If you actually spoke accurate kansaiben, I would be very surprised if anyone tried to correct you and couldn’t immediately identify what it was. If anything you’d probably have them all over you with praise about how amazing it is that a foreigner can speak a regional accent.