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Existe um crescimento elevado da oferta de produtos e serviços das empresas de teleatendimento. Porém, os operadores usuários de fones de ouvido mostram-se afetados pela exposição a ruído, podendo estar sujeitos à perda auditiva permanente e irreversível devido à exposição acima dos limites permissíveis. Os métodos tradicionais de medição da exposição a ruído não são adequados quando a fonte sonora é instalada diretamente sobre o sistema auditivo externo (orelha) através do uso de fones. Neste trabalho, a norma ISO 11904 é usada para avaliar a exposição a ruído em operadores de teleatendimento, considerando duas técnicas: cabeça artificial padronizada e microfone em ouvido real. Os resultados obtidos demonstraram que os dois métodos aplicados são eficientes e efetivos, podendo contribuir na avaliação apropriada da exposição a ruído em usuários de fones de ouvido de teleatendimento.

Research testing has led to the development of an Elastomer Particle Damper (EPD), which can add considerable damping to a structure by directing the vibration to a set of interacting elastomer particles through a rigid connection. This vibration treatment presents highly nonlinear behavior that is strongly dependent on both the vibration amplitude and frequency. Curves of damping loss factor (DLF) of an EPD system with vertical motion as a function of frequency and acceleration are reported herein. The results show that the elastomer particle damper has two distinct damping regions. The first region is related to the fluidization state of the particles, as described in the literature, obtained when the damper is subjected to vertical acceleration close to 1 g and frequencies below 50 Hz. The second region presents high values of DLF to acceleration values lower than 1 g, and the frequency range is dependent upon the stiffness of the particles. A high degree of effectiveness is achieved when the working frequency of the elastomer particle dampers is tuned to a natural frequency of a plate and when they are strategically located at points having large displacement. The performance of EPDs was compared with that of a commercial constrained layer damping installed in an aircraft floor panel. The EPDs achieved an acceleration level attenuation in the aircraft floor panel similar to that of the commercial constrained layer damping system.

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In this work, a hybrid acoustic material (HAM) is designed for broadband and low-frequency sound absorption based on the combination of two different materials: a porous layer (melamine foam) and a modified Helmholtz resonator with embedded necks (HRENs). Theoretical predictions, numerical simulations, and experimental measurements are conducted to investigate the acoustic characteristics of the HREN. The HAM absorption mechanism is presented to evaluate the broadband sound absorption by the impedance matching effect of the different structures. The results of experimental tests confirmed that the HAM has broadband sound absorption and presented good agreement with an equivalent fluid model and numerical simulations. Broadband sound absorption was comparatively evaluated by the broadband factor ([Formula: see text]), revealing the advantages due to the possible configurations of HAM in relation to HREN and melamine foam. In addition, the selection and dimensions of the HREN holes and the perforation ratio, in the range of 3%–10%, allow the hybrid sound absorber to achieve one absorption peak between 235 and 582 Hz with quasi-total absorption ([Formula: see text]). This work contributes to the understanding of sound wave propagation and broadband absorption in acoustic materials composed of different materials combined.