Block the speaker(s) or microphone(s). You won't notice a huge difference-it's primarily for the low RPM rumble that engines produce in the 1,000 to 1,500 range.
Quite frankly I'm not really sure why anyone would want to turn it off.
Yes, there is a way to test it. The procedure is outline in the service manual. You can get access to the service information at www.acdelcotechconnect.com. 3 days access is $20. You could also visit your local Chevrolet dealer.