Among the many types of foams used in structural acoustic applications, Carbon-Graphite Foams (CGF) offer several multifunctional advantages. In addition to their acoustic properties, fire resistance, low density and high strength, their excellent thermal properties make them well-suited for structural applications with an emphasis on heat management. Being a hard foam, their low-frequency (<～1000 Hz) acoustic performance requires improvement in order utilize them for creating effective broadband acoustic solutions. In this study, firstly the acoustic impedance, absorption and transmission loss of three different carbon-graphite foams are investigated using normal-incidence impedance tube testing, the influence of sample thickness and air gap spacing between CGF layers on acoustic performance is examined. Further, drawing upon previous studies, the potential to augment their low-frequency acoustic performance using various membrane-embedded configurations is evaluated. The results indicate that tailored structural configurations combining CGF with resonant mechanisms stemming from interactions of the membrane with air gaps could lead to practical solutions for multifunctional, truly broadband acoustic treatments or barriers which would be very attractive for aerospace, industrial or infrastructural applications.
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