Thanks so much, @Som and @Carlos Luna, for your encouragement and advice.

And, thanks for the info and the link, Abdullah. Unfortunately, in my personal case it's not really a matter of my hearing: I scored 97% on the test you linked to. But there's a considerable problem with how my brain processes (or fails to process) the signals my ears deliver to it: I got completely flustered over one of the questions, and started to panic until I realized it was actually an example, and the answer was <em>right there</em>. I can tell the difference between a melody and a rhythm, but can't carry the one or reliably keep the other. And I've encountered more than a little household contention over being unable to tell whether a toilet tank is filling, or if the toilet is running and someone needs to go jiggle the handle, by whether the sound of it is rising or not.

So maybe there are two questions here: one, whether a tone-deaf person could learn Mandarin; and two, a rather different question of whether <em>I</em> could learn Mandarin.

Hi, I have no idea about tone deaf person. But I think, if you really want to learn chinese, you can have a try, and maybe you will find the answer after that.

Have you been diagnosed as tone deaf? Because what you said doesn’t necessarily indicate that you are. A lot of people think they’re tone deaf because they can’t tell whether a tone is higher or lower, but that’s actually normal without musical training. Even as an amateur musician, I struggle telling whether a note is higher or lower. I used to think that I might be tone deaf.

Being tone deaf means you can’t tell apart two tones, not just which is higher and which is lower. It means if you played the highest key on a piano and the lowest key, they’d sound the same to you. It means a melody to you sounds no different than a rhythm.

Listening is a learned skills. In phonetics, a learner might not even be able to tell apart two letters. As an Arabic teacher, I’ve had students who struggled even hearing (let alone pronouncing) two letters that sound very different to a native speaker. Being tone deaf means that you not only can’t tell which tone is higher and which is lower, but also that you don’t have the capacity to learn the required skill. If you can hear something different but just not easily, what that indicates is that you have the capacity to hear something different and it can be improved with practice. It might be more difficult for you than for others, but each person has a different experience in acquiring skills.

If you haven’t been diagnosed as tone deaf, you can take this quick test to see if you actually are or not: http://tonedeaftest.com

Yeah. Tones matter but 99% of the time people will understand based on context. My tones aren't great but I can still chat comfortably with people in both Mandarin and Cantonese.

Being tone deaf prevents you from a musical career, but I doubt it would be a hindrance to learning tonal languages such as Mandarin, Cantonese, Thai, Lao and Vietnamese. One can safely say that such a large population of native speakers has a fair number of those who are tone deaf in a musical sense. These languages have a singsong character, but they aren't exactly what one may call music that needs exact tone discernment.