@bluemoondriver, the test was in 1984 and the conclusions were:
In summary, then, no evidence was provided by Tiefenbrun during this series of tests that indicates ability to identify reliably:
(a) the presence of an undriven transducer in the room,
(b) the presence of the Sony PCM-F1 digital processor in the audio chain, or
(c) the presence of the relay contacts of the A/B/X switchbox in the circuit.