It's Friday night, past midnight (so technically it's Saturday) and I can't fall asleep even though I got up at 5:10 this morning. Usually after an hour, I give up and get back up. I don't time it either. It's just that when I check the time it's always one hour. Maybe I give up too soon. Anyway, so I decided to write this little post, since I was thinking about this anyway.
I went to the Japanese Sign Language Circle meeting tonight, and after it ended, this one member was talking to me. And she says this one word that I didn't understand. It struck me as really interesting and I felt curious to know what it meant. So I repeated it exactly like she said it. And then when she starts to explain it, I realize it's the name of the store I always go to, which has a supermarket in the basement where she works. And then I'm like, "Ah! セイユウ!" And at that moment, upon hearing myself say it like I always do, I realized that my intonation for the word was different than the way she had said it and I had repeated it after her.
That was weird. It's like, "what am I, Chinese?" Have I become Chinese? I can't even understand a word when the intonation is different than what I am used to. And this is the Japanese language, mind you.
To answer the question in the title of my post: No. As Dr. J. Marvin Brown wrote in his book, "the words don't carry the meaning – the meaning carries the words."
I believe this is true in Chinese as well. If you have a single word with the wrong "tone," people aren't going to think you said something off-the-wall. It just wouldn't make sense, and so they would try to quickly figure out what you meant from the context of your conversation or your sentence. If you weren't in a conversation, meaning you don't have any context yet, then it will make it more difficult for them to come up with what you meant. Of course, if all of your "tones" are wrong then it will be just too much work for the listener, and if you have no context as well, then you might as well be speaking a foreign language to them.
Whether your language is tonal or not, it's important to speak with the right intonation because that will make it effortless for people to listen to you. If you sound funny speaking, then people will get tired of hearing you and some won't even try to listen or try to understand you.
The best way to learn how to speak properly is not through speaking, but through doing a lot of listening first and without reading during that time. If you started speaking too early, then you'll need to put in some (or a lot of) extra effort later if you want to speak with the intonation of a native speaker.
You can often see forum posts about whether tones in Chinese are important or not. I read the first page of the thread in the link, but I'm not going to be reading any more. Basically, as usual, a bunch of people say, oh yes, it's important to focus on getting the tones right of Chinese words. However, this is the wrong approach. This is the also the approach the language courses and Chinese language teachers take. Have you ever heard any learner who sounds natural from using such an approach? I have seen at least 5 Chinese dramas where a westerner in the drama speaks Chinese and none of them sound natural at all. They probably all have the wrong "tone" on a lot of words or are missing "tones" on half the words. I don't know how these people get their speaking parts.
The right approach is to get to understanding the language before you begin speaking. And I don't mean some "shortcut" understanding. A natural approach leads to natural speaking. Shortcuts lead to, well, a shortened, cut-up version of a language.
Sentence intonation is one thing I've not seen anybody talk about amongst learners of Chinese. Sentence intonation is something you can't teach or study, or look up in a book. It must come naturally through the exposure to at least hundreds of hours of the language. I'd like to write more about this at a later date. For now, what I want to say is that even if all your "tones" on words are correct, you still won't sound natural. So focusing on learning the tones of words and practicing pronunciation is not going to make you sound natural. Your speed and prosody have to be natural, not just the tones of every individual word.