Is it permissible to work on a project for a famous search engine that relies on listening to specific words (such as: songs, music, movies, and obscene language) and verifying their correct spelling to link the sound of the letter to its written form, knowing that the declared goal is to link the sound of the letter to its written form and not the word itself? And is it permissible for a Muslim to overlook hearing obscene language in this work?

The ruling on your work depends on the purpose of the project and the nature of the audible words. If the purpose of the project is permissible and the speech is not obscene, then the work is permissible. However, if the purpose is unlawful, such as searching for forbidden songs, then it is not permissible, due to the Almighty’s saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." Likewise, working is not permissible if it requires listening to obscene or foul language, because anything forbidden to be spoken is forbidden to be listened to, and the listener is a partner to the speaker. And whoever guards his hearing from obscene speech has acted upon the Almighty’s saying: "And do not pursue that of which you have no knowledge. Indeed, the hearing, the sight, and the heart - all of these will be questioned."