Extended Data Fig. 4: Characterizations of the CNT film.

a, Experimental setup for measuring the sound pressure and the surface vibration displacement. b, Acoustic pressure amplitude spectra measured near the CNT film (solid curve) and the loudspeaker (dashed curve). c, Vibration displacements spectra measured by laser vibrometry. The solid and dashed curves represent surface displacement on the CNT film and the traditional paper basin loudspeaker, respectively. d, Photograph of the measurement setup for electrical impedance analysis. Inset: enlarged view of the single sample. e, Experimentally measured amplitude and phase of the impedance curve. f, Experimentally measured directivity pattern.