Tracecross

hey. I have a 07 Scion tC and I'm hearing a very annoying noise in my left door.. I remove the inside panel about 5 times trying to find where the noise is coming from, but some how I couldn't find it. the noise is coming from at the top where you usually rest your hand when driving somewhere at the top of the door in the middle..it sound as if something fell off in the there and can't come out.. it wasn't there when I first bought the car but after awhile I started hearing it and it so annoying.. can anyone tell me what it is?