A very popular videos in Youtube surveyed about audio CAPTCHAs. SOME OF THEM ARE STILL IN USE NOW!!!
Some Website You Can Try Them Directly!!!
https://www.arkoselabs.com/arkose-matchkey/
https://service.mtcaptcha.com/mtcv1/demo/index.html
https://gt4.geetest.com/demov4/voice-float-en.html
https://www.google.com/recaptcha/api2/demo (Please use Incognito browsing)