DEFINITION:

Acoustic measurements deal with pressure field using microphones and pressure transducers, in association if needed with other probes, as accelerometers or DLV. It constitutes the basis for experimental studies concerning noise pollution, noise reduction, acoustic detection and ranging, and acoustic fatigue. Depending of
the application, attention is focused on the radiated far-field (vehicle certification), the near acoustic field (cabin noise, vibroacoustics), the characterisation of noise sources (physical phenomena responsible for vehicle noise emission such as turbomachinery noise, jet noise, airframe noise, installation effects), the acoustic imaging (detection and ranging). Measurements are made at model scale (anechoic room, windtunnels) or at full scale. Acoustic measurements are strongly coupled with signal processing, in particular concerning localisation and active noise control. They are also strongly interested in psychoacoustics and the definition of noise annoyance indicators.

(Source: ACARE Domain 213)

SUBDOMAINS:

1. Sensors and transducers: condenser microphone, loudspeakers, acoustic driver, accelerometer, sound intensity probe, smart transducer, pistonphone, DLV
2. Units: physical units (Pa, dB), psychoacoustical units (dBA, PNdB, EPNdB, Leq,…)
3. Common measurements: calibration, absorption, convection, refraction, reverberation, near-field and farfield, intensimetry
4. Machinery and airframe noise measurements: anechoïc room, reverberation chamber, wind tunnel, flight tests, internal and external noise
5. Noise source localisation and ranging: microphone array, acoustic mirror
6. Acoustic signal recording and processing: narrow band frequency analysis, third octave and octave bands, correlations, random noise, impulsive noise
7. Certification procedures
8. Acoustic detection
9. Active noise control