Using pressure taps and high-frequency surface pressure microphones flush-mounted on airfoils measured in wind tunnels and on an operating wind turbine blade, the characteristics of stall are analyzed.
Broadband resonant devices (e.g., for ultrasonic cleaning and drilling) and nonresonant devices (e.g., accelerometers, pressure gauges, microphone pickups) are dominated by ceramic piezoelectrics.
Eavesdropping on the ocean, though, is more complicated, on a technological level, than listening to the world up above, because the amount of pressure a microphone must withstand differs greatly depending on how deep it dives.
If, in the case of a pressure operated microphone, one tries to avoid this trouble by determining the pressure calibration by the resonant tube1 or thermophone methods and by calculating the increase in sensitivity due to reflection from the microphone, the difficulty, if not impossibility, of making this calculation rigidly for practical forms of microphone is encountered.
Sound particle velocities were measured with an Emkay NR 3158 pressure gradient microphone at the position of the fly.
The system was calibrated using a 40BP 0.25-inch pressure condenser microphone, 26AC preamplifier and 12AR power supply (all G.R.A.S).
The output was calibrated using a type 4192 pressure field microphone with a 4153 artificial ear and a 2260 sound level meter (Brűel & Kjær, Naerum, Denmark).
The system was calibrated using a 40BP 0.25-inch pressure condenser microphone, 26AC preamplifier and 12AR power supply (all G.R.A.S, Holte, Denmark) attached to a calibrated 1-mm-diameter probe positioned near the entrance to the ear canal.
However, the recent research shows that the acoustic sensing using pressure based microphones have significant scope in the area of fault diagnosis.
