Sterility of transducer. Frequency response Second order system of mass spring and damper. Moving mass is fluid in tube, ie Stiffness is force require to move liquid , where P is pressure, V is volume of transducer. Resonant angular frequency is Increase by increasing diameter of tube and stiffness of transducer, and decreasing length. Bubbles in transducer reduce its effective stiffness.
Transducer is commonly a diaphragm and strain gauges.
Depends on change in dimensions. Simplest and cheapest. Fine wires strung from diaphragm to body. Maximises strain in gauges for given chamber compliance. Higher output but also higher thermal sensitivity.