Fig. 3: Experimental verification in an open resonator.
a Image of 3D printed full (left) and half (right) acoustic resonator. b Transmission measurement system. c Full transmission spectrum in the frequency range 2000–6000 Hz. Red, blue and magenta lines represent full resonator (Lx = Ly = Lz = 60 mm) with yc = zc = 0 mm, yc = 1 mm and zc = 0 mm, and yc = zc = 4 mm, respectively; Black and green lines represent half resonator (Lx = 30 mm, Ly = Lz = 60 mm) with yc = zc = 0 mm, and yc = 1 mm and zc = 0 mm. Eight BICs are observed and labelled as 1–8. d–g zoom in transmission spectrum in the frequency range 2700–3200 Hz (d), 4050–4250 Hz (e), 4400–5600 Hz (f), and 5750–5950 Hz (g). h pressure field distribution of eight BICs in the full and half resonator, which is also correlated to peaks 1–8 in the transmission spectrum.
