The term 'Sounds of Uncertainty' refers to four distinct vocalizations that are used to express hesitation, confusion, or doubt. These sounds are ers (3 letters), haws (4 letters), ums (3 letters), and uhs (3 letters). Ers is a sound made in the back of the throat, haws is a sound made with the lips, ums is a sound made with the lips and tongue, and uhs is a sound made with the lips and teeth. All of these sounds are used to indicate that the speaker is uncertain or unsure of what they are saying.