This is a vintage analogue speaker frequency-response measuring device identical to the one originally used in the National Research Council's anechoic chamber. They were very expensive devices in there day and really quite astonishingly accurate. The biggest drawback was the inability to store the data, other than the graph sheets the B&K produced of each sweep. Ian still has his volumes of binders from the 1980s full of these B&K sweeps. This vintage piece of history sits in our Loudspeaker Design Lab.