3D internal noise simulation for vibro-acoustic comfort assessment: an application proposal for AW-109 helicopter

摘要

The evaluation and assessment of vibro-acoustic comfort inside civil aircraft requires the knowledge of two different classes of information: the physical feature of both noise and vibration fields and the way the passenger reacts to those stimuli. This paper describes design and performance analysis of a ground-based mock-up for 3D reconstruction of the internal vibro-acoustic field of a helicopter cabin (GINS: Ground-based Internal Noise Simulator); the facility was assembled at the CIRA premise of Capua (IT) as part of the EU-funded project FRIENDCOPTER and was aimed at reproducing the spatial distribution of the interior noise of an AW109. The internal acoustic environment was simulated through implementation of the auralisation technique; the reproduced vibro-acoustic field was experimentally measured during in-flight tests on a AW109 helicopter at the Agusta premise of Cascina Costa (IT). The ground-based simulator (GINS) was assembled by integrating the reproducing technology and the CIRA semi-anechoic chamber; a listening test was carried out in order to verify how reliable the noise field 3D spatial reconstruction appeared from a subjective point of view. In details, the listening tests were aimed at evaluating how clearly a good theoretical noise control technique could be identified in the passengers' reactions; those reactions were collected and evaluated through suitable questionnaires that were developed by the psycho-acoustic experts of the University of Oldenburg (D) for the EU-funded project IDEA PACI. The questionnaires analysis showed that the GINS can provide realistic internal acoustic reproductions and that the relevant features of the sound quality are easily perceived by the listening people; this implies that such a simulator can be effectively employed for comfort studies.