Hoarse voice is an abnormal change in your voice caused by disorders in the vocal cords of the voice box, or larynx. The vocal cords are normally open but make sounds by coming together when you speak, sing or hum.hen your voice is hoarse, it is an indication that these vibrations of the vocal folds are being hindered by mucus, swellings, obstructions or other changes in the surface of the larynx.