How does acid reflux cause hoarseness?

Backflow: Backflow of stomach contents (stomach acid and pepsin) into the throat and larynx can lead to inflammation and irritation. This chronic exposure can lead to an assortment of symptoms including voice change, loss of vocal range, sore throat, dry cough, foreign body sensation in the throat, throat clearing among others. Heartburn is not a frequent symptom in patients who reflux into the throat.

Chronic irritation: Stomach acid is coating your vocal cords and larynx. This essentially causes a low-grade chemical burn and causes swelling of your vocal cords. Your vocal cords can't vibrate as well and hoarseness is the result. Sometimes the larynx will try to recruit other parts of the larynx to help with voice production and this can also lead to even more hoarseness (functional dysphonia).