macbook recognises xternal mic, audacity won't


I’m using a Macbook Pro with Catalina 10.15.5 - all latest updates installed.

Using a splitter adapter in order to connect a microphone (without it, Macbooks only recognise the built in mic as an input)

So: I go to System Preferences > Sound and EXTERNAL MICROPHONE is there and selected.

But when I download the latest version of Audacity today - 2.4.2. - the software only recognises BUILT-IN MICROPHONE.

I looked on FAQ - the advice was to return to the Sound menu on my Macbook and change the Output port…? I am not being very precise here (please excuse me - I am an anthropologist, and my expert teenage son is out for the evening) but it was indicated that I could somehow change the port to xxxxxx (and there was a string of letters and numbers).

I would have been capable of that, but the Sound menu does not offer me any options to change ports. I attach a screenshot: it does not even offer me the option to switch back to the built-in mic.

BUT - the reverse is true if I open Audacity. In that case, the only option is Built-in Microphone/Built-in Output (another fascinating action-shot attached for y’all).

Can anyone offer me some advice? I would be very grateful.
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What is a “splitter adapter”? Does it have a make and model?

Which model of Macbook Pro. Look in Apple menu > About this Mac.

With the adapter connected, in Audacity do Transport > Rescan Audio Devices. Then try to set the input to the “external microphone”.

– Bill

I think that’s a reference to the newer Macs which are radio terminals and have only one connection for everything, correct me, including charging.

So there is no such thing as giving a USB microphone its own connection. There is always going to be some octopus device in the middle.

But to the question, I’ve had audio devices vanish if I chose stereo/mono incorrectly. The built-in microphone will cheerfully mount as either one which can give you a false sense of security, but many external devices won’t. They just won’t show up.