The most common culprit for that rasp in your voice? An infection in your airways. A cold, the flu, bronchitis, or another upper respiratory infection can make your vocal cords swell temporarily — also known as laryngitis.
Just like viruses, outdoor allergies to certain trees and plants in bloom can cause laryngitis. The irritation and drainage that hit your airways might also make you clear your throat more often and inflame your vocal cords.