Is it possible to detect when the system is recording a sound and then perform some action on Python?

Question

I began learning Python a few days ago, and i was wondering about a practical use for a program.
Then i came up with the following: if my brother is in his room recording himself playing guitar, a led plugged to the usb and wired so it's outside his door lights up, and then i'll know he's recording and i'll take care not to make any noises.
The main questions are:

• How Python can detect any recording going on in the system?
• How would i interface with the usb so i can actually turn the led on?

Answer 1

to interact with USB, you can read this related question.

to detect recording, you will have to tell us on which operating system your program is intented to run (but i am not sure it is possible to detect that another application is recording)