filter (electronics or software to separate unwanted signal)

benefit (be or provide a benefit to)

useless, deadhead, good-for-nothing, a piece of shit / (politics) lame duck

audio quality

betterment, improvement, amelioration

(transitive) to improve, to make better / (intransitive) for something to improve on its own

improvement, an action taken to improve / improvement, a spontaneous change for the better

a wave

container, vessel / a tool, a utensil / one's degree of ability: talent, calibre / female genitalia: a vagina

a female given name