Usage patterns
〈人〉の陰口を言うto badmouth someone behind their back
She likes to badmouth her coworkers behind their backs.
陰口を聞くto overhear backbiting talk
I happened to overhear people badmouthing me.
陰口を叩かれるto be badmouthed by others
In my new department, people often badmouthed me behind my back.
Expressions
陰口を叩くbackbite; speak ill of someone behind their back