What was found
INFLIGHT, CREW REPORTED ACRID ODOR IN THE FLIGHT DECK AND SMOKE COMING OUT OF THE CENTER CONSOLE, BETWEEN THE CENTER AUDIO PANEL AND THE FIRST OBSERVER AUDIO PANEL. EMERGENCY DECLARED, FLIGHT LANDED WITHOUT INCIDENT. FOUND THE FIRST OBSERVER AUDIO SELECT PANEL AT FAULT. PLACARDED AUDIO SELECT PANEL INOPERATIVE IAW MEL. REPLACED FIRST OBSERVER AUDIO CONTROL PANEL. SYSTEM GROUND CHECK NORMAL OPERATION.