The original scientific uncaptcha2 paper proposes a method to solves Google’s Audio reCAPTCHA with Google’s own Speech-to-Text API. The idea of the attack is very simple: You grab the mp3 file and you submit it to Google’s. own Speech to Text API. Google will return the correct answer in over 97% (* Edit: 91] of all cases. The figure 91% comes from the original uncaptch2 repository, but their Proof of Concept code does not work anymore (as the authors predicted correctly)”]
Source: https://incolumitas.com/2021/01/02/breaking-audio-recaptcha-with-googles-own-speech-to-text-api/