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Acoustic insulation represents a very important issue in many fields of acoustic engineering. This issue is generally assessed through one characteristic named sound insulation parameter or noise reduction level (NR).
Research for materials with high mechanical-resistance-to-weight ratio promotes sandwich composite structures, but these ones present lower acoustic insulation performances than metallic homogeneous structures. Thus, the correct identification and assessment of the main transmission loss factor drivers for sandwich composite structures are essential to improve their acoustic isolation efficiency.
In space industry, acoustic characterization of sandwich composite structures, such as launcher fairing, is a key point for payload and equipment acoustic comfort assessment, when facing severe broadband environment during lift-off phase.
In this paper, the overall approach of acoustic specification to payload is detailed with a particular attention given to the noise reduction level estimation of the fairing structure. The first part will present the Vibroacoustic logic used for acoustic specification. Then, the method employed for fairing exterior acoustic field prediction will briefly be described. Next, the modelling of the composite structure depending on the frequency domain is studied. Finally, the methods used for Vibroacoustic computations as well as comparison with measurements are exposed.
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