I want to create a TRRS splitter / joiner that can be used to combine two 3.5mm jacks, one for headphones and one for a microphone, into a single 3.5mm TRRS male jack. It'll use the CTIA standard so that I'd be able to connect it to a standard PC or mobile phone headset port.
The issue is that the sort of microphone I want to connect (here's an example) uses a TRS jack, and with a TRRS cable only one contact / wire is used to carry the mic signal (which with the CTIA standard is the sleeve). I'm fairly certain it's an electret microphone, it's mono, and it's unbalanced.
What do I do with the ring contact on the mic's TRS jack?
Here's a (crude) illustration of the issue:
Perhaps I connect both the mic tip and ring to the TRRS sleeve? Or maybe the mic ring should be connected to the ground?