High background noise when using USB-4432

[diesel logie]

Hi, I tried to use microphone to record sound pressure signals by using USB-4432. But there are very high background noise when I play back the signal measured. 

I also tried using PXI-4462, and there is no such background noise.

The VI program I used is the same one, as attached. Then why USB-4432 will cause that noise?

[ManLongAtNI]

Can you quantify the amount of noise you are seeing? Is it NI USB-443x Specifications? It may be difficult to identify the source of the noise since the two products are different form factors.

Regards,

Glenn