Figure 6
From: Laser-assisted see-through technology for locating sound sources inside a structure
(a) Front view of the projector. Airflows were drawn into the projector from the bottom and ejected through front and top grids of the projector. (b) Spectrogram of the aerodynamically-generated sound produced by airflows inside the projector. Because blower speed was constant and low, so was the Reynold’s number. Thus, the frequencies of aerodynamically-generated sound were below 1000 Hz.
