get sound from dual monitors

[debraleecarlin]

I have two new ViewSonic VA2855SM monitors with sound. They are connected to an HP docking station with an HP laptop running Windows 7. One monitor is connected VGA to VGA, the other from the monitor HDMI to the dock DP port via an adaptor. The dual display is fine, but no sound come from the monitors. I installed the driver from ViewSonic prior to setup, and confirmed the driver is installed.
The mixer icon in the system tray indicates sound is being processed. I checked Control Panel>Sound and a VA2844 SERIES monitor is checked as the default device. Everything looks good to me, but I am not a hardware person. Please advise. Thank you.

 

[debraleecarlin]

This is debraleecarlin again. I forgot to mention I have connected the audio from the headphone port to the Dock via a splitter (also tried to connect it directly to the PC). I saw a post that said you are unlikely to get quality sound from both monitors; I would be happy just to get sound from one.