Obtaining dynamic mechanical properties of viscoelastic solid materials can be challenging at acoustic frequencies. Commercially available characterization equipment is typically limited to about 500 Hz. Time–temperature superposition extrapolation to higher frequencies is indirect and time consuming. Resonance methods do not yield broadband data and fail for materials with high loss moduli. A new relatively simple characterization method, relying on bending wave excitation and laser Doppler vibrometer measurement, is proposed. Complex elastic moduli and phase speeds are now attainable to frequencies beyond 10 kHz with high reproducibility. The materials under test are an array of polyurea aerogels with fixed chemical composition but different nanomorphologies. Low cost and ease of synthesis add appeal to materials already noted for their sound transmission loss performance.