Structural Response
Dynamic amplification occurs when high-frequency airborne pressure waves match the internal mechanical modes of a sensor package. Acoustic resonance describes this physical phenomenon, where external sound energy drives microscopic MEMS elements or cavity structures into unwanted high-amplitude standing waves. The condition introduces zero-shift errors and output noise when fluid or gas pressure fluctuations pass through package vents.
It stops governing system behavior once the excitation frequency moves outside the mechanical bandwidth of the internal cavity.
Frequency Coupling
Energy transfer from ambient acoustic fields into microscopic proof masses alters the transducer bias. Sound pressure waves bypass traditional elastomeric isolation mounts by acting directly on exposed substrate surfaces. Under intense acoustic fields, pressure peaks create differential forces across sensitive diaphragms.
This interaction drives high-frequency standing waves within internal package voids.
Sensor Susceptibility
Package cavity dimensions set the natural acoustic modes of micro-machined devices. Piezoresistive and capacitive accelerometers suffer localized bias shifts when ambient noise spectra contain energy at cavity modes. Silicon seals and fluid-filled cavities damp these modes differently depending on gas density.
Physical shielding reduces high-frequency pressure transmission across the sensor housing.
Mitigation Technique
Acoustic damping materials absorb airborne energy before sound waves enter the sensor enclosure. Damping foams and acoustic baffles attenuate high-amplitude acoustic peaks. Damped enclosures shift standing wave modes outside operational bandwidths.
