What Causes Difficulty In Speech & Change In Voice Modulation?

dr.my name is s.pascaran 51 years old from sri lanka wants to consult a ent specialist .the decease which i have is i had a cough in the night in three months back . now i my voice is different change and difficult speak loud .i am a continiouly mobile user and a smoker.pls instruct me to consult a ent specialist in first week in december 2010.