Aerospace acoustic measurement encompasses a wide range of demanding applications: jet engine and rocket noise characterisation at extreme sound pressure levels, structural acoustic fatigue testing of airframe panels and fuselage sections, cabin noise and passenger comfort assessment in development aircraft, and ground vibration testing. Defence applications include acoustic signature analysis and detection system calibration. Each of these requires measurement microphones and signal conditioning specified for the particular sound pressure level range, frequency bandwidth, and environmental conditions of the test.
Rocket and jet engine acoustic testing involves sound pressure levels that can exceed 165 dB SPL in the near field — well beyond the range of standard 1/2-inch microphones. 1/4-inch microphones with higher upper dynamic range limits are specified for these applications. For structural acoustic fatigue monitoring on airframe test specimens, microphones and accelerometers must tolerate extended vibration exposure. Cabin noise testing uses arrays of microphones at defined head positions.
Aerospace qualification and certification test programmes typically require measurement uncertainty documentation that is formally incorporated into the test report. ISO/IEC 17025 accredited calibration with stated expanded measurement uncertainty is the standard documentary requirement. Calibration traceability documentation must be retained for the lifetime of the programme, which may extend to 20 years or more for safety-critical components. PLACID provides accredited calibration certificates with full traceability chain documentation.
1/4-inch Class 1 measurement microphones with high SPL capability are the appropriate choice for near-field jet and rocket acoustic testing. For cabin noise and interior acoustic measurement, 1/2-inch free-field Class 1 microphones are used at lower SPL. PLACID PM400 series 1/4-inch microphones provide the high-SPL dynamic range required for structural acoustic fatigue testing environments. Contact PLACID to discuss sensor selection and uncertainty budgeting for your specific aerospace test programme.