Plangency is a term used to describe the quality of sound that is loud, deep, and resonant. It is often used to describe musical instruments such as drums, bells, and gongs. The term comes from the Latin word 'plangere, ' which means 'to beat or strike.' Plangency is also used to describe the sound of a person's voice when they are speaking with emotion or intensity. It is a quality that can be heard in many forms of music, poetry, and literature.