horn (automobile etc) · loudspeaker · brass wind instrument · trumpet · suona suǒ nà

The train slowed and blared its horn as it approached the railway crossing.

I bet you'd never heard of a Stroh violin before Tom Waits dug it back up! Anyway, it used a large metal horn as its resonator instead of a wooden box so it could be picked up better by recording equipment before the late 1920s.