laryngitis, inflammation of the mucous membrane of the voice box, or larynx, usually accompanied by hoarseness, sore throat, and coughing. Acute laryngitis is often a secondary bacterial infection triggered by infecting agents causing such illnesses as colds, measles, whooping cough, or influenza. It may also result from straining the voice, drinking hot liquids, or exposure to irritating gases. In chronic laryngitis, inflammation of the mucous membrane of the larynx persists. When such a condition continues for long periods, the membrane becomes irreversibly thickened and the voice permanently changed. Laryngitis resulting from weakened laryngeal muscles is common in singers, teachers, and others who use the voice professionally.