measuring and displaying -12db on an lcd

I have a large piece of test equipment that is only being used to test the audio section of a circuit board by injecting a -10db, 1Khz signal into the input and expecting to see -12db on the output. If the output is -12db then the circuit passes the test.
Is there a way to design a circuit using the arduino so I can automate this test? the -10db on the input should be eaily do-able. It's measuring the -12db output that I have no idea on how to tackle.

Mike

It's measuring the -12db output that I have no idea on how to tackle

Well the simplest way I can think is to take that -12db output audio AC signal and rectify and filter it and measure it with a Arduino analog input pin as a DC voltage proportional to the signals level.

Lefty