Boom boom - the sound of cannons came from the distance.
Tips
usage
Chinese onomatopoeia typically follows the pattern [sound]的一声 - literally 'one sound of [sound].' So 嘣的一声 = 'a bang sound.' You can also double it (嘣嘣) for repeated sounds.
Left mouth radical in onomatopoeia mode - locks the character into the sound-effect family alongside 咚, 砰, 噔. Whenever you see 口 next to a familiar phonetic, expect an imitative noise rather than a literal mouth meaning.
Right 崩 supplies the sound bēng exactly. It also adds a perfect semantic flavour: 崩 means 'to collapse, to burst,' which is precisely the kind of explosive boom 嘣 imitates - a balloon popping, a heart-thump, a sudden crack.
