Cfrock
Keep it strong
Not user error on my part - it's because the mic is just bad. Why else would we NOT have voice chat?
The DS mic was capable of supporting voice chat.
Perhaps the issue some people have stems from the fact that DS games which use the microphone don't require you to actually blow on it. The mic responds to sound, not air. The act of blowing causes the air to whistle over the tiny hole and the mic registers the sound, not the action. This how it 'knows' you are blowing. You could sing to your DS and as long as it pick up the noise, it'll think you're blowing on it. You could shout abusive names at it and it'd think you were blowing.
I remember playing the Ace Attorney games. They have a feature which allows you to say 'Objection!' when you wish to object and I used this feature a lot because I could say whatever I wanted. 'That's a damn lie!' or 'You can't handle the truth!' and every time I spoke it worked because the mic just wants a noise. I could have farted on it and got it to work, but I didn't want to get my DS all smelly. When Spirit Tracks wants you to blow on the flute the mic can fairly easily get confused by ambient noises. This is likely the reason why some people notice it playing notes when they aren't blowing. In the same way, they may produce no notes when they are blowing because too much noise in the mic and it just doesn't respond. Again, going back to Ace Attorney, you could never actually shout 'Objection!' because it would be too loud and not register. You had to just speak the word at a normal volume.
Not gonna say this is the root cause of everyone's issue with the Spirit Flute but it's something worth keeping in mind.