Graph 1 shows the in-room response measured by Newport Test Labs, with the speaker placed well clear of all boundaries so that there wouldn't be any boundary-induced reinforcement of low frequencies. The trace is the averaged result of nine frequency response measurements, made with the microphone positioned at nine different points in front of the speaker, with the central point on-axis with the tweeter. All responses were obtained using pink noise as the stimulus.
You can see that above the low-frequency roll-o— (which is the inevitable result of the absence of boundary reinforcement and the relatively that of the speaker itself — its response extends well above 20kHz, as shown in Graph 2.
