EVAL-ADSP-SC589 static / sound surge disconnects

Hello,

We have purchased ~6 of EVAL-ADSP-SC589 boards and will order another 6 shortly.  We are building prototype audiology systems.

We had no issues last summer or fall but once winter started and the humidity dropped we started having lots of USB microphone disconnects due to nearby static discharge.  Grounding ourselves before we approach the system would address the issue but we cannot expect our customers to do that so we are looking for a better solution.  Our equipment is designed to evaluate hearing in ~50 people a day so that's a lot of opportunities for static discharge..

Our USB cable is ~8' long and connects to the included short adapter cable that plugs into the SC589 USB micro jack.

We are wondering if you any of you any advise about how to avoid static disconnection issues?...or get the host controller to reconnect after a disruption?

The microphone will disconnect immediately anytime there is any nearby static discharge (not even on the microphone or soundcard).  

We have replaced the microphone and cable to no avail.

We have tried earth grounding the SC589 but it made no difference. It seems the static discharges are large enough so the RF itself is causing a USB signal interruption.

After the microphone has been 'disconnected' due to static its power light is still on so it is physically connected to the soundcard but the static interrupts the signal enough to have to reboot the soundcard for it to work correctly again (this takes ~60 seconds so undesirable..)

Often the sound card will not recognize USB devices being plugged or unplugged.  It seems there is a USB host side issue.  Even if the signal/connection is momentarily disrupted the software should enable reconnection without having to reboot the SC589? 

It's possible that the static discharge causes a surge in microphone power consumption that the SC589 can't keep up with as placing a powered hub in series with the mic (but right at the 589 not half way) seems to help... the 589 power supply may be large enough but the power draw from the usb micro port too limited to maintain a connection during a surge?  A few times we had similar disconnects with a loud noise/clap right by the mic..

Thank you for any advise or fix you can offer!

Best Regards,

Pete