This paper presents linear viscoelastic measurement on a large frequency range (10(-2)- 10(8) Hz) for cross-linked polymer open-cell foams of same density and different pore sizes. This large extension of frequency range is obtained by the validation of a frequency-temperature superposition principle, commonly used with polymers. At higher frequencies, the shear moduli are independent of the pore size. In acoustical insulation range (1 Hz-16 kHz), the shear moduli decreases with the foams' pore size. (C) 2009 Acoustical Society of America