Vocal Fold Scarring
Vocal fold scarring can occur following the presence of a lesion, changes to the tissue following surgery, and if the vocal fold tissue is continuously irritated from vocal abuse and misuse. Just like with scars you can see on your arms or legs, scar tissue is more stiff than regular tissue. When the vocal folds accumulate scar tissue, they become more stiff and are not as pliable. This reduction in pliability results in a reduced mucosal wave and the voice sounding dysphonic (unpleasant to the ear). Those suffering from vocal fold scars typically lose vocal flexibility for pitch changes, fatigue easily, have a quieter sound and sound rough or strained.
Sources: Clinical Voice Pathology: Theory and Management 4th Edition Stemple, Glaze & Klaben