I know this is the internet so my factless post will be ignored by 99.9% of readers, but I have a tidbit of real information to share about the speakers in the Model 3.
My source being: I met a guy that works high up for a company that makes sound systems for cars. We are talking a supplier for Volkswagen group (Audi, Skoda, …), Renault, Opel, Peugeot, Citroen, Ford, GM, … and also Tesla.
Many of the soundsystems in cars are shared between vehicles, and dirt cheap to car makers because of the economies of scale.
When I heard he also supplied for Tesla I asked everything I could, and here is what he told me: