I have noticed this noise cause when I tap at the back of my ipod touch 5g under the camera region. I went through all forums on Google and found out that it is because the auto focus mechanism. They say that try focus on the object in camera app, this rattling noise should disappear when auto-focusing is working. But it seems not so. There is no noise when shaking, my device is working fine but when tap on the back, there is a noise. Anyone can assure me that this is normal to my device? It's kinda an annoyance to hear this noise. I put ipod back down softly on the pillow, that rattling noise is produced. However, it's minimal issue but I just want to know anyone experiences the same thing as me? It happens when tapping ONLY and NOT WHEN SHAKING. Thanks for reading.