Breakdown of Stanno facendo un baccano snervante, devono smetterla.
un
a / an (masculine)
fare
to do / to make
stare
to stay, to feel, to be
dovere
must
Questions & Answers about Stanno facendo un baccano snervante, devono smetterla.
Why is there a la attached to smettere in smetterla, and what does it refer to?
This is a lexicalized pronominal verb. The pronoun la doesn't refer to a specific feminine noun in the sentence, especially since the noise is masculine (il baccano). Instead, it acts as a fixed part of the expression. The la refers vaguely to the annoying action or situation itself, giving it the meaning of "to stop it" or "to knock it off."
Could I just say devono smettere instead of devono smetterla?
Yes, devono smettere is grammatically correct and simply means "they must stop." However, adding la makes the demand much more emphatic and colloquial. It translates closer to "they must knock it off" or "they need to cut it out." It is the most natural choice when you are actively annoyed by someone's behavior.
If I wanted to explicitly say "they must stop making a racket," how would I connect that action to smetterla?
You would use the preposition di followed by the infinitive verb. For example: Devono smetterla di fare baccano (They must stop making a racket). The grammatical structure to remember is always smetterla di + [infinitive].
What exactly is a baccano and how is it different from a rumore?