Continuous system wav sounds when using a USB 2.0 hug

Hi,

I plugged a USB 2.0 hub into my pc and plugged 2 Seagate ex hd's into it. System connection wav files sounded constantly for about 5 minutes after I plugged the drives in even though the drives were turned off. When I turned the drives on, the system connection wav files continued again for a few more minutes. Is this normal? It didn't do that when each drive was plugged into separate ports in my pc. My pc gave me one sound when the drive was turned on and one sound when I turned the drive off.

Denise