What makes the 3DS recognize the audio input through a splitter?

I'm playing around with the microphone and I'm having a weird issue, specifically with the splitter. So, I put a splitter in the audio port of the n3DS and plugged the microphone input directly into the speaker output of my laptop using an auxiliary cable, and the n3DS didn't recognize it. So I tried it with my o3DS, still nothing. It kept taking audio input from the microphone and not from the auxiliary cable. However, if I plug the microphone input directly into my DSi's speaker output, it works perfectly! And it works every time without fail. Same with my Nexus 4. But then again it doesn't work at all with my Nexus 10. For some reason, the n3DS doesn't seem to recognize the audio coming through the splitter for my laptop, my o3DS, my Nexus 10, but perfectly for my DSi and my Nexus 4, and I have no clue why this is or what decides it. Does anyone have any clue what causes the 3DS to switch from the internal microphone to an external one? I can't figure it out. Check out these pictures. I'm guessing there must be a difference in some audio ports or something that could be causing this, but I really don't know. I've had trouble getting it to recognize it before with PetitModem, and I found it'd only recognize my old laptop and not my new one. So I really have no clue what's causing this. I'm just using MICTEST and MICDATA to determine if it's "connected" or not, it really just says it's connected if it detects any audio.

I'd love a solid answer to this as well. For me, the problem is the 3DS only detects audio after a lot of fiddling. The other day I probably spent a couple of hours trying to get it to work to no avail. I love using P/SEND (it takes a fraction of the time Petit Modem takes), but it requires you have an aux cable. I wish there was a more reliable solution. Could the new audio DLC help with this sort of thing?

I'm over simplifying a whole lot here. 3.5mm jacks that have a mic and phone are 4-pole (TRRS) connectors. Usually they only have three poles; the fourth one facilitates the mic. The 3ds has a 4-pole socket, so it accepts TRRS plugs. If there cables you're using don't have 4-pole pins, it probably won't work. You can tell it's TRRS if the metal plug has 3 stripes on it.

If it's a problem with the cables, why do they work on some devices perfectly but not at all on others? I'll order some TRRS cables, hopefully that will fix it. I do believe these are TRS and not TRRS cables.

I'm over simplifying a whole lot here. 3.5mm jacks that have a mic and phone are 4-pole (TRRS) connectors. Usually they only have three poles; the fourth one facilitates the mic. The 3ds has a 4-pole socket, so it accepts TRRS plugs. If there cables you're using don't have 4-pole pins, it probably won't work. You can tell it's TRRS if the metal plug has 3 stripes on it.

If it's a problem with the cables, why do they work on some devices perfectly but not at all on others? I'll order some TRRS cables, hopefully that will fix it. I do believe these are TRS and not TRRS cables.

I actually don't know if getting all new cables is the solution. I don't know why it works on some and not others, hmm.

I'm over simplifying a whole lot here. 3.5mm jacks that have a mic and phone are 4-pole (TRRS) connectors. Usually they only have three poles; the fourth one facilitates the mic. The 3ds has a 4-pole socket, so it accepts TRRS plugs. If there cables you're using don't have 4-pole pins, it probably won't work. You can tell it's TRRS if the metal plug has 3 stripes on it.

If it's a problem with the cables, why do they work on some devices perfectly but not at all on others? I'll order some TRRS cables, hopefully that will fix it. I do believe these are TRS and not TRRS cables.

I actually don't know if getting all new cables is the solution. I don't know why it works on some and not others, hmm.

Yeah, I got my TRRS cables and they don't work at all. If you plug them into the 3DS directly or plug them into the splitter, both ways the 3DS won't recognize them. So far I've got the 3DS to recognize TRS cables using a splitter, and only on specific devices.

Could it have something to do with the grounding?