Fig. 5: Two output-coupled sensors.

a, Frequency response (f1 = 14.2 kHz, f2 = 10.1 kHz) shown for three different coupling strengths b12 = b21 = b = 0 (black), b = 1.050 (red) and b = 1.875 (blue). The sound signal consists of a linear frequency chirp in the range of 8.5–15.5 kHz with a sound pressure amplitude of 0.107 Pa. Increasing the coupling strength yields a stronger response of the sensors at their respective resonance frequency as well as an increase in sensor bandwidth, that is, the range of sound frequencies, to which the sensors respond (the blue curve between 10 and 14 kHz). b, Schematic of the sensor system with output-signal coupling. c, Equations of actuation signals for output-signal-coupled sensors (Methods).